// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Driver for the Conexant CX2584x Audio/Video decoder chip and related cores
 *
 *  Integrated Consumer Infrared Controller
 *
 *  Copyright (C) 2010  Andy Walls <awalls@md.metrocast.net>
 */

#include <linux/slab.h>
#include <linux/kfifo.h>
#include <linux/module.h>
#include <media/drv-intf/cx25840.h>
#include <media/rc-core.h>

#include "cx25840-core.h"

static unsigned int ir_debug;
module_param(ir_debug, int, 0644);
MODULE_PARM_DESC(ir_debug, "enable integrated IR debug messages");

#define CX25840_IR_REG_BASE     0x200

#define CX25840_IR_CNTRL_REG    0x200
#define CNTRL_WIN_3_3   0x00000000
#define CNTRL_WIN_4_3   0x00000001
#define CNTRL_WIN_3_4   0x00000002
#define CNTRL_WIN_4_4   0x00000003
#define CNTRL_WIN       0x00000003
#define CNTRL_EDG_NONE  0x00000000
#define CNTRL_EDG_FALL  0x00000004
#define CNTRL_EDG_RISE  0x00000008
#define CNTRL_EDG_BOTH  0x0000000C
#define CNTRL_EDG       0x0000000C
#define CNTRL_DMD       0x00000010
#define CNTRL_MOD       0x00000020
#define CNTRL_RFE       0x00000040
#define CNTRL_TFE       0x00000080
#define CNTRL_RXE       0x00000100
#define CNTRL_TXE       0x00000200
#define CNTRL_RIC       0x00000400
#define CNTRL_TIC       0x00000800
#define CNTRL_CPL       0x00001000
#define CNTRL_LBM       0x00002000
#define CNTRL_R         0x00004000

#define CX25840_IR_TXCLK_REG    0x204
#define TXCLK_TCD       0x0000FFFF

#define CX25840_IR_RXCLK_REG    0x208
#define RXCLK_RCD       0x0000FFFF

#define CX25840_IR_CDUTY_REG    0x20C
#define CDUTY_CDC       0x0000000F

#define CX25840_IR_STATS_REG    0x210
#define STATS_RTO       0x00000001
#define STATS_ROR       0x00000002
#define STATS_RBY       0x00000004
#define STATS_TBY       0x00000008
#define STATS_RSR       0x00000010
#define STATS_TSR       0x00000020

#define CX25840_IR_IRQEN_REG    0x214
#define IRQEN_RTE       0x00000001
#define IRQEN_ROE       0x00000002
#define IRQEN_RSE       0x00000010
#define IRQEN_TSE       0x00000020
#define IRQEN_MSK       0x00000033

#define CX25840_IR_FILTR_REG    0x218
#define FILTR_LPF       0x0000FFFF

#define CX25840_IR_FIFO_REG     0x23C
#define FIFO_RXTX       0x0000FFFF
#define FIFO_RXTX_LVL   0x00010000
#define FIFO_RXTX_RTO   0x0001FFFF
#define FIFO_RX_NDV     0x00020000
#define FIFO_RX_DEPTH   8
#define FIFO_TX_DEPTH   8

#define CX25840_VIDCLK_FREQ     108000000 /* 108 MHz, BT.656 */
#define CX25840_IR_REFCLK_FREQ  (CX25840_VIDCLK_FREQ / 2)

/*
 * We use this union internally for convenience, but callers to tx_write
 * and rx_read will be expecting records of type struct ir_raw_event.
 * Always ensure the size of this union is dictated by struct ir_raw_event.
 */
union cx25840_ir_fifo_rec {
        u32 hw_fifo_data;
        struct ir_raw_event ir_core_data;
};

#define CX25840_IR_RX_KFIFO_SIZE    (256 * sizeof(union cx25840_ir_fifo_rec))
#define CX25840_IR_TX_KFIFO_SIZE    (256 * sizeof(union cx25840_ir_fifo_rec))

struct cx25840_ir_state {
        struct i2c_client *c;

        struct v4l2_subdev_ir_parameters rx_params;
        struct mutex rx_params_lock; /* protects Rx parameter settings cache */
        atomic_t rxclk_divider;
        atomic_t rx_invert;

        struct kfifo rx_kfifo;
        spinlock_t rx_kfifo_lock; /* protect Rx data kfifo */

        struct v4l2_subdev_ir_parameters tx_params;
        struct mutex tx_params_lock; /* protects Tx parameter settings cache */
        atomic_t txclk_divider;
};

static inline struct cx25840_ir_state *to_ir_state(struct v4l2_subdev *sd)
{
        struct cx25840_state *state = to_state(sd);
        return state ? state->ir_state : NULL;
}


/*
 * Rx and Tx Clock Divider register computations
 *
 * Note the largest clock divider value of 0xffff corresponds to:
 *      (0xffff + 1) * 1000 / 108/2 MHz = 1,213,629.629... ns
 * which fits in 21 bits, so we'll use unsigned int for time arguments.
 */
static inline u16 count_to_clock_divider(unsigned int d)
{
        if (d > RXCLK_RCD + 1)
                d = RXCLK_RCD;
        else if (d < 2)
                d = 1;
        else
                d--;
        return (u16) d;
}

static inline u16 ns_to_clock_divider(unsigned int ns)
{
        return count_to_clock_divider(
                DIV_ROUND_CLOSEST(CX25840_IR_REFCLK_FREQ / 1000000 * ns, 1000));
}

static inline unsigned int clock_divider_to_ns(unsigned int divider)
{
        /* Period of the Rx or Tx clock in ns */
        return DIV_ROUND_CLOSEST((divider + 1) * 1000,
                                 CX25840_IR_REFCLK_FREQ / 1000000);
}

static inline u16 carrier_freq_to_clock_divider(unsigned int freq)
{
        return count_to_clock_divider(
                          DIV_ROUND_CLOSEST(CX25840_IR_REFCLK_FREQ, freq * 16));
}

static inline unsigned int clock_divider_to_carrier_freq(unsigned int divider)
{
        return DIV_ROUND_CLOSEST(CX25840_IR_REFCLK_FREQ, (divider + 1) * 16);
}

static inline u16 freq_to_clock_divider(unsigned int freq,
                                        unsigned int rollovers)
{
        return count_to_clock_divider(
                   DIV_ROUND_CLOSEST(CX25840_IR_REFCLK_FREQ, freq * rollovers));
}

static inline unsigned int clock_divider_to_freq(unsigned int divider,
                                                 unsigned int rollovers)
{
        return DIV_ROUND_CLOSEST(CX25840_IR_REFCLK_FREQ,
                                 (divider + 1) * rollovers);
}

/*
 * Low Pass Filter register calculations
 *
 * Note the largest count value of 0xffff corresponds to:
 *      0xffff * 1000 / 108/2 MHz = 1,213,611.11... ns
 * which fits in 21 bits, so we'll use unsigned int for time arguments.
 */
static inline u16 count_to_lpf_count(unsigned int d)
{
        if (d > FILTR_LPF)
                d = FILTR_LPF;
        else if (d < 4)
                d = 0;
        return (u16) d;
}

static inline u16 ns_to_lpf_count(unsigned int ns)
{
        return count_to_lpf_count(
                DIV_ROUND_CLOSEST(CX25840_IR_REFCLK_FREQ / 1000000 * ns, 1000));
}

static inline unsigned int lpf_count_to_ns(unsigned int count)
{
        /* Duration of the Low Pass Filter rejection window in ns */
        return DIV_ROUND_CLOSEST(count * 1000,
                                 CX25840_IR_REFCLK_FREQ / 1000000);
}

static inline unsigned int lpf_count_to_us(unsigned int count)
{
        /* Duration of the Low Pass Filter rejection window in us */
        return DIV_ROUND_CLOSEST(count, CX25840_IR_REFCLK_FREQ / 1000000);
}

/*
 * FIFO register pulse width count computations
 */
static u32 clock_divider_to_resolution(u16 divider)
{
        /*
         * Resolution is the duration of 1 tick of the readable portion of
         * of the pulse width counter as read from the FIFO.  The two lsb's are
         * not readable, hence the << 2.  This function returns ns.
         */
        return DIV_ROUND_CLOSEST((1 << 2)  * ((u32) divider + 1) * 1000,
                                 CX25840_IR_REFCLK_FREQ / 1000000);
}

static u64 pulse_width_count_to_ns(u16 count, u16 divider)
{
        u64 n;
        u32 rem;

        /*
         * The 2 lsb's of the pulse width timer count are not readable, hence
         * the (count << 2) | 0x3
         */
        n = (((u64) count << 2) | 0x3) * (divider + 1) * 1000; /* millicycles */
        rem = do_div(n, CX25840_IR_REFCLK_FREQ / 1000000);     /* / MHz => ns */
        if (rem >= CX25840_IR_REFCLK_FREQ / 1000000 / 2)
                n++;
        return n;
}

#if 0
/* Keep as we will need this for Transmit functionality */
static u16 ns_to_pulse_width_count(u32 ns, u16 divider)
{
        u64 n;
        u32 d;
        u32 rem;

        /*
         * The 2 lsb's of the pulse width timer count are not accessible, hence
         * the (1 << 2)
         */
        n = ((u64) ns) * CX25840_IR_REFCLK_FREQ / 1000000; /* millicycles */
        d = (1 << 2) * ((u32) divider + 1) * 1000; /* millicycles/count */
        rem = do_div(n, d);
        if (rem >= d / 2)
                n++;

        if (n > FIFO_RXTX)
                n = FIFO_RXTX;
        else if (n == 0)
                n = 1;
        return (u16) n;
}

#endif
static unsigned int pulse_width_count_to_us(u16 count, u16 divider)
{
        u64 n;
        u32 rem;

        /*
         * The 2 lsb's of the pulse width timer count are not readable, hence
         * the (count << 2) | 0x3
         */
        n = (((u64) count << 2) | 0x3) * (divider + 1);    /* cycles      */
        rem = do_div(n, CX25840_IR_REFCLK_FREQ / 1000000); /* / MHz => us */
        if (rem >= CX25840_IR_REFCLK_FREQ / 1000000 / 2)
                n++;
        return (unsigned int) n;
}

/*
 * Pulse Clocks computations: Combined Pulse Width Count & Rx Clock Counts
 *
 * The total pulse clock count is an 18 bit pulse width timer count as the most
 * significant part and (up to) 16 bit clock divider count as a modulus.
 * When the Rx clock divider ticks down to 0, it increments the 18 bit pulse
 * width timer count's least significant bit.
 */
static u64 ns_to_pulse_clocks(u32 ns)
{
        u64 clocks;
        u32 rem;
        clocks = CX25840_IR_REFCLK_FREQ / 1000000 * (u64) ns; /* millicycles  */
        rem = do_div(clocks, 1000);                         /* /1000 = cycles */
        if (rem >= 1000 / 2)
                clocks++;
        return clocks;
}

static u16 pulse_clocks_to_clock_divider(u64 count)
{
        do_div(count, (FIFO_RXTX << 2) | 0x3);

        /* net result needs to be rounded down and decremented by 1 */
        if (count > RXCLK_RCD + 1)
                count = RXCLK_RCD;
        else if (count < 2)
                count = 1;
        else
                count--;
        return (u16) count;
}

/*
 * IR Control Register helpers
 */
enum tx_fifo_watermark {
        TX_FIFO_HALF_EMPTY = 0,
        TX_FIFO_EMPTY      = CNTRL_TIC,
};

enum rx_fifo_watermark {
        RX_FIFO_HALF_FULL = 0,
        RX_FIFO_NOT_EMPTY = CNTRL_RIC,
};

static inline void control_tx_irq_watermark(struct i2c_client *c,
                                            enum tx_fifo_watermark level)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~CNTRL_TIC, level);
}

static inline void control_rx_irq_watermark(struct i2c_client *c,
                                            enum rx_fifo_watermark level)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~CNTRL_RIC, level);
}

static inline void control_tx_enable(struct i2c_client *c, bool enable)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~(CNTRL_TXE | CNTRL_TFE),
                        enable ? (CNTRL_TXE | CNTRL_TFE) : 0);
}

static inline void control_rx_enable(struct i2c_client *c, bool enable)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~(CNTRL_RXE | CNTRL_RFE),
                        enable ? (CNTRL_RXE | CNTRL_RFE) : 0);
}

static inline void control_tx_modulation_enable(struct i2c_client *c,
                                                bool enable)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~CNTRL_MOD,
                        enable ? CNTRL_MOD : 0);
}

static inline void control_rx_demodulation_enable(struct i2c_client *c,
                                                  bool enable)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~CNTRL_DMD,
                        enable ? CNTRL_DMD : 0);
}

static inline void control_rx_s_edge_detection(struct i2c_client *c,
                                               u32 edge_types)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~CNTRL_EDG_BOTH,
                        edge_types & CNTRL_EDG_BOTH);
}

static void control_rx_s_carrier_window(struct i2c_client *c,
                                        unsigned int carrier,
                                        unsigned int *carrier_range_low,
                                        unsigned int *carrier_range_high)
{
        u32 v;
        unsigned int c16 = carrier * 16;

        if (*carrier_range_low < DIV_ROUND_CLOSEST(c16, 16 + 3)) {
                v = CNTRL_WIN_3_4;
                *carrier_range_low = DIV_ROUND_CLOSEST(c16, 16 + 4);
        } else {
                v = CNTRL_WIN_3_3;
                *carrier_range_low = DIV_ROUND_CLOSEST(c16, 16 + 3);
        }

        if (*carrier_range_high > DIV_ROUND_CLOSEST(c16, 16 - 3)) {
                v |= CNTRL_WIN_4_3;
                *carrier_range_high = DIV_ROUND_CLOSEST(c16, 16 - 4);
        } else {
                v |= CNTRL_WIN_3_3;
                *carrier_range_high = DIV_ROUND_CLOSEST(c16, 16 - 3);
        }
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~CNTRL_WIN, v);
}

static inline void control_tx_polarity_invert(struct i2c_client *c,
                                              bool invert)
{
        cx25840_and_or4(c, CX25840_IR_CNTRL_REG, ~CNTRL_CPL,
                        invert ? CNTRL_CPL : 0);
}

/*
 * IR Rx & Tx Clock Register helpers
 */
static unsigned int txclk_tx_s_carrier(struct i2c_client *c,
                                       unsigned int freq,
                                       u16 *divider)
{
        *divider = carrier_freq_to_clock_divider(freq);
        cx25840_write4(c, CX25840_IR_TXCLK_REG, *divider);
        return clock_divider_to_carrier_freq(*divider);
}

static unsigned int rxclk_rx_s_carrier(struct i2c_client *c,
                                       unsigned int freq,
                                       u16 *divider)
{
        *divider = carrier_freq_to_clock_divider(freq);
        cx25840_write4(c, CX25840_IR_RXCLK_REG, *divider);
        return clock_divider_to_carrier_freq(*divider);
}

static u32 txclk_tx_s_max_pulse_width(struct i2c_client *c, u32 ns,
                                      u16 *divider)
{
        u64 pulse_clocks;

        if (ns > IR_MAX_DURATION)
                ns = IR_MAX_DURATION;
        pulse_clocks = ns_to_pulse_clocks(ns);
        *divider = pulse_clocks_to_clock_divider(pulse_clocks);
        cx25840_write4(c, CX25840_IR_TXCLK_REG, *divider);
        return (u32) pulse_width_count_to_ns(FIFO_RXTX, *divider);
}

static u32 rxclk_rx_s_max_pulse_width(struct i2c_client *c, u32 ns,
                                      u16 *divider)
{
        u64 pulse_clocks;

        if (ns > IR_MAX_DURATION)
                ns = IR_MAX_DURATION;
        pulse_clocks = ns_to_pulse_clocks(ns);
        *divider = pulse_clocks_to_clock_divider(pulse_clocks);
        cx25840_write4(c, CX25840_IR_RXCLK_REG, *divider);
        return (u32) pulse_width_count_to_ns(FIFO_RXTX, *divider);
}

/*
 * IR Tx Carrier Duty Cycle register helpers
 */
static unsigned int cduty_tx_s_duty_cycle(struct i2c_client *c,
                                          unsigned int duty_cycle)
{
        u32 n;
        n = DIV_ROUND_CLOSEST(duty_cycle * 100, 625); /* 16ths of 100% */
        if (n != 0)
                n--;
        if (n > 15)
                n = 15;
        cx25840_write4(c, CX25840_IR_CDUTY_REG, n);
        return DIV_ROUND_CLOSEST((n + 1) * 100, 16);
}

/*
 * IR Filter Register helpers
 */
static u32 filter_rx_s_min_width(struct i2c_client *c, u32 min_width_ns)
{
        u32 count = ns_to_lpf_count(min_width_ns);
        cx25840_write4(c, CX25840_IR_FILTR_REG, count);
        return lpf_count_to_ns(count);
}

/*
 * IR IRQ Enable Register helpers
 */
static inline void irqenable_rx(struct v4l2_subdev *sd, u32 mask)
{
        struct cx25840_state *state = to_state(sd);

        if (is_cx23885(state) || is_cx23887(state))
                mask ^= IRQEN_MSK;
        mask &= (IRQEN_RTE | IRQEN_ROE | IRQEN_RSE);
        cx25840_and_or4(state->c, CX25840_IR_IRQEN_REG,
                        ~(IRQEN_RTE | IRQEN_ROE | IRQEN_RSE), mask);
}

static inline void irqenable_tx(struct v4l2_subdev *sd, u32 mask)
{
        struct cx25840_state *state = to_state(sd);

        if (is_cx23885(state) || is_cx23887(state))
                mask ^= IRQEN_MSK;
        mask &= IRQEN_TSE;
        cx25840_and_or4(state->c, CX25840_IR_IRQEN_REG, ~IRQEN_TSE, mask);
}

/*
 * V4L2 Subdevice IR Ops
 */
int cx25840_ir_irq_handler(struct v4l2_subdev *sd, u32 status, bool *handled)
{
        struct cx25840_state *state = to_state(sd);
        struct cx25840_ir_state *ir_state = to_ir_state(sd);
        struct i2c_client *c = NULL;
        unsigned long flags;

        union cx25840_ir_fifo_rec rx_data[FIFO_RX_DEPTH];
        unsigned int i, j, k;
        u32 events, v;
        int tsr, rsr, rto, ror, tse, rse, rte, roe, kror;
        u32 cntrl, irqen, stats;

        *handled = false;
        if (ir_state == NULL)
                return -ENODEV;

        c = ir_state->c;

        /* Only support the IR controller for the CX2388[57] AV Core for now */
        if (!(is_cx23885(state) || is_cx23887(state)))
                return -ENODEV;

        cntrl = cx25840_read4(c, CX25840_IR_CNTRL_REG);
        irqen = cx25840_read4(c, CX25840_IR_IRQEN_REG);
        if (is_cx23885(state) || is_cx23887(state))
                irqen ^= IRQEN_MSK;
        stats = cx25840_read4(c, CX25840_IR_STATS_REG);

        tsr = stats & STATS_TSR; /* Tx FIFO Service Request */
        rsr = stats & STATS_RSR; /* Rx FIFO Service Request */
        rto = stats & STATS_RTO; /* Rx Pulse Width Timer Time Out */
        ror = stats & STATS_ROR; /* Rx FIFO Over Run */

        tse = irqen & IRQEN_TSE; /* Tx FIFO Service Request IRQ Enable */
        rse = irqen & IRQEN_RSE; /* Rx FIFO Service Request IRQ Enable */
        rte = irqen & IRQEN_RTE; /* Rx Pulse Width Timer Time Out IRQ Enable */
        roe = irqen & IRQEN_ROE; /* Rx FIFO Over Run IRQ Enable */

        v4l2_dbg(2, ir_debug, sd, "IR IRQ Status:  %s %s %s %s %s %s\n",
                 tsr ? "tsr" : "   ", rsr ? "rsr" : "   ",
                 rto ? "rto" : "   ", ror ? "ror" : "   ",
                 stats & STATS_TBY ? "tby" : "   ",
                 stats & STATS_RBY ? "rby" : "   ");

        v4l2_dbg(2, ir_debug, sd, "IR IRQ Enables: %s %s %s %s\n",
                 tse ? "tse" : "   ", rse ? "rse" : "   ",
                 rte ? "rte" : "   ", roe ? "roe" : "   ");

        /*
         * Transmitter interrupt service
         */
        if (tse && tsr) {
                /*
                 * TODO:
                 * Check the watermark threshold setting
                 * Pull FIFO_TX_DEPTH or FIFO_TX_DEPTH/2 entries from tx_kfifo
                 * Push the data to the hardware FIFO.
                 * If there was nothing more to send in the tx_kfifo, disable
                 *      the TSR IRQ and notify the v4l2_device.
                 * If there was something in the tx_kfifo, check the tx_kfifo
                 *      level and notify the v4l2_device, if it is low.
                 */
                /* For now, inhibit TSR interrupt until Tx is implemented */
                irqenable_tx(sd, 0);
                events = V4L2_SUBDEV_IR_TX_FIFO_SERVICE_REQ;
                v4l2_subdev_notify(sd, V4L2_SUBDEV_IR_TX_NOTIFY, &events);
                *handled = true;
        }

        /*
         * Receiver interrupt service
         */
        kror = 0;
        if ((rse && rsr) || (rte && rto)) {
                /*
                 * Receive data on RSR to clear the STATS_RSR.
                 * Receive data on RTO, since we may not have yet hit the RSR
                 * watermark when we receive the RTO.
                 */
                for (i = 0, v = FIFO_RX_NDV;
                     (v & FIFO_RX_NDV) && !kror; i = 0) {
                        for (j = 0;
                             (v & FIFO_RX_NDV) && j < FIFO_RX_DEPTH; j++) {
                                v = cx25840_read4(c, CX25840_IR_FIFO_REG);
                                rx_data[i].hw_fifo_data = v & ~FIFO_RX_NDV;
                                i++;
                        }
                        if (i == 0)
                                break;
                        j = i * sizeof(union cx25840_ir_fifo_rec);
                        k = kfifo_in_locked(&ir_state->rx_kfifo,
                                            (unsigned char *) rx_data, j,
                                            &ir_state->rx_kfifo_lock);
                        if (k != j)
                                kror++; /* rx_kfifo over run */
                }
                *handled = true;
        }

        events = 0;
        v = 0;
        if (kror) {
                events |= V4L2_SUBDEV_IR_RX_SW_FIFO_OVERRUN;
                v4l2_err(sd, "IR receiver software FIFO overrun\n");
        }
        if (roe && ror) {
                /*
                 * The RX FIFO Enable (CNTRL_RFE) must be toggled to clear
                 * the Rx FIFO Over Run status (STATS_ROR)
                 */
                v |= CNTRL_RFE;
                events |= V4L2_SUBDEV_IR_RX_HW_FIFO_OVERRUN;
                v4l2_err(sd, "IR receiver hardware FIFO overrun\n");
        }
        if (rte && rto) {
                /*
                 * The IR Receiver Enable (CNTRL_RXE) must be toggled to clear
                 * the Rx Pulse Width Timer Time Out (STATS_RTO)
                 */
                v |= CNTRL_RXE;
                events |= V4L2_SUBDEV_IR_RX_END_OF_RX_DETECTED;
        }
        if (v) {
                /* Clear STATS_ROR & STATS_RTO as needed by resetting hardware */
                cx25840_write4(c, CX25840_IR_CNTRL_REG, cntrl & ~v);
                cx25840_write4(c, CX25840_IR_CNTRL_REG, cntrl);
                *handled = true;
        }
        spin_lock_irqsave(&ir_state->rx_kfifo_lock, flags);
        if (kfifo_len(&ir_state->rx_kfifo) >= CX25840_IR_RX_KFIFO_SIZE / 2)
                events |= V4L2_SUBDEV_IR_RX_FIFO_SERVICE_REQ;
        spin_unlock_irqrestore(&ir_state->rx_kfifo_lock, flags);

        if (events)
                v4l2_subdev_notify(sd, V4L2_SUBDEV_IR_RX_NOTIFY, &events);
        return 0;
}

/* Receiver */
static int cx25840_ir_rx_read(struct v4l2_subdev *sd, u8 *buf, size_t count,
                              ssize_t *num)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);
        bool invert;
        u16 divider;
        unsigned int i, n;
        union cx25840_ir_fifo_rec *p;
        unsigned u, v, w;

        if (ir_state == NULL)
                return -ENODEV;

        invert = (bool) atomic_read(&ir_state->rx_invert);
        divider = (u16) atomic_read(&ir_state->rxclk_divider);

        n = count / sizeof(union cx25840_ir_fifo_rec)
                * sizeof(union cx25840_ir_fifo_rec);
        if (n == 0) {
                *num = 0;
                return 0;
        }

        n = kfifo_out_locked(&ir_state->rx_kfifo, buf, n,
                             &ir_state->rx_kfifo_lock);

        n /= sizeof(union cx25840_ir_fifo_rec);
        *num = n * sizeof(union cx25840_ir_fifo_rec);

        for (p = (union cx25840_ir_fifo_rec *) buf, i = 0; i < n; p++, i++) {

                if ((p->hw_fifo_data & FIFO_RXTX_RTO) == FIFO_RXTX_RTO) {
                        /* Assume RTO was because of no IR light input */
                        u = 0;
                        w = 1;
                } else {
                        u = (p->hw_fifo_data & FIFO_RXTX_LVL) ? 1 : 0;
                        if (invert)
                                u = u ? 0 : 1;
                        w = 0;
                }

                v = (unsigned) pulse_width_count_to_ns(
                                  (u16)(p->hw_fifo_data & FIFO_RXTX), divider) / 1000;
                if (v > IR_MAX_DURATION)
                        v = IR_MAX_DURATION;

                p->ir_core_data = (struct ir_raw_event)
                        { .pulse = u, .duration = v, .timeout = w };

                v4l2_dbg(2, ir_debug, sd, "rx read: %10u ns  %s  %s\n",
                         v, u ? "mark" : "space", w ? "(timed out)" : "");
                if (w)
                        v4l2_dbg(2, ir_debug, sd, "rx read: end of rx\n");
        }
        return 0;
}

static int cx25840_ir_rx_g_parameters(struct v4l2_subdev *sd,
                                      struct v4l2_subdev_ir_parameters *p)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);

        if (ir_state == NULL)
                return -ENODEV;

        mutex_lock(&ir_state->rx_params_lock);
        memcpy(p, &ir_state->rx_params,
                                      sizeof(struct v4l2_subdev_ir_parameters));
        mutex_unlock(&ir_state->rx_params_lock);
        return 0;
}

static int cx25840_ir_rx_shutdown(struct v4l2_subdev *sd)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);
        struct i2c_client *c;

        if (ir_state == NULL)
                return -ENODEV;

        c = ir_state->c;
        mutex_lock(&ir_state->rx_params_lock);

        /* Disable or slow down all IR Rx circuits and counters */
        irqenable_rx(sd, 0);
        control_rx_enable(c, false);
        control_rx_demodulation_enable(c, false);
        control_rx_s_edge_detection(c, CNTRL_EDG_NONE);
        filter_rx_s_min_width(c, 0);
        cx25840_write4(c, CX25840_IR_RXCLK_REG, RXCLK_RCD);

        ir_state->rx_params.shutdown = true;

        mutex_unlock(&ir_state->rx_params_lock);
        return 0;
}

static int cx25840_ir_rx_s_parameters(struct v4l2_subdev *sd,
                                      struct v4l2_subdev_ir_parameters *p)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);
        struct i2c_client *c;
        struct v4l2_subdev_ir_parameters *o;
        u16 rxclk_divider;

        if (ir_state == NULL)
                return -ENODEV;

        if (p->shutdown)
                return cx25840_ir_rx_shutdown(sd);

        if (p->mode != V4L2_SUBDEV_IR_MODE_PULSE_WIDTH)
                return -ENOSYS;

        c = ir_state->c;
        o = &ir_state->rx_params;

        mutex_lock(&ir_state->rx_params_lock);

        o->shutdown = p->shutdown;

        p->mode = V4L2_SUBDEV_IR_MODE_PULSE_WIDTH;
        o->mode = p->mode;

        p->bytes_per_data_element = sizeof(union cx25840_ir_fifo_rec);
        o->bytes_per_data_element = p->bytes_per_data_element;

        /* Before we tweak the hardware, we have to disable the receiver */
        irqenable_rx(sd, 0);
        control_rx_enable(c, false);

        control_rx_demodulation_enable(c, p->modulation);
        o->modulation = p->modulation;

        if (p->modulation) {
                p->carrier_freq = rxclk_rx_s_carrier(c, p->carrier_freq,
                                                     &rxclk_divider);

                o->carrier_freq = p->carrier_freq;

                p->duty_cycle = 50;
                o->duty_cycle = p->duty_cycle;

                control_rx_s_carrier_window(c, p->carrier_freq,
                                            &p->carrier_range_lower,
                                            &p->carrier_range_upper);
                o->carrier_range_lower = p->carrier_range_lower;
                o->carrier_range_upper = p->carrier_range_upper;

                p->max_pulse_width =
                        (u32) pulse_width_count_to_ns(FIFO_RXTX, rxclk_divider);
        } else {
                p->max_pulse_width =
                            rxclk_rx_s_max_pulse_width(c, p->max_pulse_width,
                                                       &rxclk_divider);
        }
        o->max_pulse_width = p->max_pulse_width;
        atomic_set(&ir_state->rxclk_divider, rxclk_divider);

        p->noise_filter_min_width =
                            filter_rx_s_min_width(c, p->noise_filter_min_width);
        o->noise_filter_min_width = p->noise_filter_min_width;

        p->resolution = clock_divider_to_resolution(rxclk_divider);
        o->resolution = p->resolution;

        /* FIXME - make this dependent on resolution for better performance */
        control_rx_irq_watermark(c, RX_FIFO_HALF_FULL);

        control_rx_s_edge_detection(c, CNTRL_EDG_BOTH);

        o->invert_level = p->invert_level;
        atomic_set(&ir_state->rx_invert, p->invert_level);

        o->interrupt_enable = p->interrupt_enable;
        o->enable = p->enable;
        if (p->enable) {
                unsigned long flags;

                spin_lock_irqsave(&ir_state->rx_kfifo_lock, flags);
                kfifo_reset(&ir_state->rx_kfifo);
                spin_unlock_irqrestore(&ir_state->rx_kfifo_lock, flags);
                if (p->interrupt_enable)
                        irqenable_rx(sd, IRQEN_RSE | IRQEN_RTE | IRQEN_ROE);
                control_rx_enable(c, p->enable);
        }

        mutex_unlock(&ir_state->rx_params_lock);
        return 0;
}

/* Transmitter */
static int cx25840_ir_tx_write(struct v4l2_subdev *sd, u8 *buf, size_t count,
                               ssize_t *num)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);

        if (ir_state == NULL)
                return -ENODEV;

#if 0
        /*
         * FIXME - the code below is an incomplete and untested sketch of what
         * may need to be done.  The critical part is to get 4 (or 8) pulses
         * from the tx_kfifo, or converted from ns to the proper units from the
         * input, and push them off to the hardware Tx FIFO right away, if the
         * HW TX fifo needs service.  The rest can be pushed to the tx_kfifo in
         * a less critical timeframe.  Also watch out for overruning the
         * tx_kfifo - don't let it happen and let the caller know not all his
         * pulses were written.
         */
        u32 *ns_pulse = (u32 *) buf;
        unsigned int n;
        u32 fifo_pulse[FIFO_TX_DEPTH];
        u32 mark;

        /* Compute how much we can fit in the tx kfifo */
        n = CX25840_IR_TX_KFIFO_SIZE - kfifo_len(ir_state->tx_kfifo);
        n = min(n, (unsigned int) count);
        n /= sizeof(u32);

        /* FIXME - turn on Tx Fifo service interrupt
         * check hardware fifo level, and other stuff
         */
        for (i = 0; i < n; ) {
                for (j = 0; j < FIFO_TX_DEPTH / 2 && i < n; j++) {
                        mark = ns_pulse[i] & LEVEL_MASK;
                        fifo_pulse[j] = ns_to_pulse_width_count(
                                         ns_pulse[i] &
                                               ~LEVEL_MASK,
                                         ir_state->txclk_divider);
                        if (mark)
                                fifo_pulse[j] &= FIFO_RXTX_LVL;
                        i++;
                }
                kfifo_put(ir_state->tx_kfifo, (u8 *) fifo_pulse,
                                                               j * sizeof(u32));
        }
        *num = n * sizeof(u32);
#else
        /* For now enable the Tx FIFO Service interrupt & pretend we did work */
        irqenable_tx(sd, IRQEN_TSE);
        *num = count;
#endif
        return 0;
}

static int cx25840_ir_tx_g_parameters(struct v4l2_subdev *sd,
                                      struct v4l2_subdev_ir_parameters *p)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);

        if (ir_state == NULL)
                return -ENODEV;

        mutex_lock(&ir_state->tx_params_lock);
        memcpy(p, &ir_state->tx_params,
                                      sizeof(struct v4l2_subdev_ir_parameters));
        mutex_unlock(&ir_state->tx_params_lock);
        return 0;
}

static int cx25840_ir_tx_shutdown(struct v4l2_subdev *sd)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);
        struct i2c_client *c;

        if (ir_state == NULL)
                return -ENODEV;

        c = ir_state->c;
        mutex_lock(&ir_state->tx_params_lock);

        /* Disable or slow down all IR Tx circuits and counters */
        irqenable_tx(sd, 0);
        control_tx_enable(c, false);
        control_tx_modulation_enable(c, false);
        cx25840_write4(c, CX25840_IR_TXCLK_REG, TXCLK_TCD);

        ir_state->tx_params.shutdown = true;

        mutex_unlock(&ir_state->tx_params_lock);
        return 0;
}

static int cx25840_ir_tx_s_parameters(struct v4l2_subdev *sd,
                                      struct v4l2_subdev_ir_parameters *p)
{
        struct cx25840_ir_state *ir_state = to_ir_state(sd);
        struct i2c_client *c;
        struct v4l2_subdev_ir_parameters *o;
        u16 txclk_divider;

        if (ir_state == NULL)
                return -ENODEV;

        if (p->shutdown)
                return cx25840_ir_tx_shutdown(sd);

        if (p->mode != V4L2_SUBDEV_IR_MODE_PULSE_WIDTH)
                return -ENOSYS;

        c = ir_state->c;
        o = &ir_state->tx_params;
        mutex_lock(&ir_state->tx_params_lock);

        o->shutdown = p->shutdown;

        p->mode = V4L2_SUBDEV_IR_MODE_PULSE_WIDTH;
        o->mode = p->mode;

        p->bytes_per_data_element = sizeof(union cx25840_ir_fifo_rec);
        o->bytes_per_data_element = p->bytes_per_data_element;

        /* Before we tweak the hardware, we have to disable the transmitter */
        irqenable_tx(sd, 0);
        control_tx_enable(c, false);

        control_tx_modulation_enable(c, p->modulation);
        o->modulation = p->modulation;

        if (p->modulation) {
                p->carrier_freq = txclk_tx_s_carrier(c, p->carrier_freq,
                                                     &txclk_divider);
                o->carrier_freq = p->carrier_freq;

                p->duty_cycle = cduty_tx_s_duty_cycle(c, p->duty_cycle);
                o->duty_cycle = p->duty_cycle;

                p->max_pulse_width =
                        (u32) pulse_width_count_to_ns(FIFO_RXTX, txclk_divider);
        } else {
                p->max_pulse_width =
                            txclk_tx_s_max_pulse_width(c, p->max_pulse_width,
                                                       &txclk_divider);
        }
        o->max_pulse_width = p->max_pulse_width;
        atomic_set(&ir_state->txclk_divider, txclk_divider);

        p->resolution = clock_divider_to_resolution(txclk_divider);
        o->resolution = p->resolution;

        /* FIXME - make this dependent on resolution for better performance */
        control_tx_irq_watermark(c, TX_FIFO_HALF_EMPTY);

        control_tx_polarity_invert(c, p->invert_carrier_sense);
        o->invert_carrier_sense = p->invert_carrier_sense;

        /*
         * FIXME: we don't have hardware help for IO pin level inversion
         * here like we have on the CX23888.
         * Act on this with some mix of logical inversion of data levels,

         * carrier polarity, and carrier duty cycle.
         */
        o->invert_level = p->invert_level;

        o->interrupt_enable = p->interrupt_enable;
        o->enable = p->enable;
        if (p->enable) {
                /* reset tx_fifo here */
                if (p->interrupt_enable)
                        irqenable_tx(sd, IRQEN_TSE);
                control_tx_enable(c, p->enable);
        }

        mutex_unlock(&ir_state->tx_params_lock);
        return 0;
}


/*
 * V4L2 Subdevice Core Ops support
 */
int cx25840_ir_log_status(struct v4l2_subdev *sd)
{
        struct cx25840_state *state = to_state(sd);
        struct i2c_client *c = state->c;
        char *s;
        int i, j;
        u32 cntrl, txclk, rxclk, cduty, stats, irqen, filtr;

        /* The CX23888 chip doesn't have an IR controller on the A/V core */
        if (is_cx23888(state))
                return 0;

        cntrl = cx25840_read4(c, CX25840_IR_CNTRL_REG);
        txclk = cx25840_read4(c, CX25840_IR_TXCLK_REG) & TXCLK_TCD;
        rxclk = cx25840_read4(c, CX25840_IR_RXCLK_REG) & RXCLK_RCD;
        cduty = cx25840_read4(c, CX25840_IR_CDUTY_REG) & CDUTY_CDC;
        stats = cx25840_read4(c, CX25840_IR_STATS_REG);
        irqen = cx25840_read4(c, CX25840_IR_IRQEN_REG);
        if (is_cx23885(state) || is_cx23887(state))
                irqen ^= IRQEN_MSK;
        filtr = cx25840_read4(c, CX25840_IR_FILTR_REG) & FILTR_LPF;

        v4l2_info(sd, "IR Receiver:\n");
        v4l2_info(sd, "\tEnabled:                           %s\n",
                  cntrl & CNTRL_RXE ? "yes" : "no");
        v4l2_info(sd, "\tDemodulation from a carrier:       %s\n",
                  cntrl & CNTRL_DMD ? "enabled" : "disabled");
        v4l2_info(sd, "\tFIFO:                              %s\n",
                  cntrl & CNTRL_RFE ? "enabled" : "disabled");
        switch (cntrl & CNTRL_EDG) {
        case CNTRL_EDG_NONE:
                s = "disabled";
                break;
        case CNTRL_EDG_FALL:
                s = "falling edge";
                break;
        case CNTRL_EDG_RISE:
                s = "rising edge";
                break;
        case CNTRL_EDG_BOTH:
                s = "rising & falling edges";
                break;
        default:
                s = "??? edge";
                break;
        }
        v4l2_info(sd, "\tPulse timers' start/stop trigger:  %s\n", s);
        v4l2_info(sd, "\tFIFO data on pulse timer overflow: %s\n",
                  cntrl & CNTRL_R ? "not loaded" : "overflow marker");
        v4l2_info(sd, "\tFIFO interrupt watermark:          %s\n",
                  cntrl & CNTRL_RIC ? "not empty" : "half full or greater");
        v4l2_info(sd, "\tLoopback mode:                     %s\n",
                  cntrl & CNTRL_LBM ? "loopback active" : "normal receive");
        if (cntrl & CNTRL_DMD) {
                v4l2_info(sd, "\tExpected carrier (16 clocks):      %u Hz\n",
                          clock_divider_to_carrier_freq(rxclk));
                switch (cntrl & CNTRL_WIN) {
                case CNTRL_WIN_3_3:
                        i = 3;
                        j = 3;
                        break;
                case CNTRL_WIN_4_3:
                        i = 4;
                        j = 3;
                        break;
                case CNTRL_WIN_3_4:
                        i = 3;
                        j = 4;
                        break;
                case CNTRL_WIN_4_4:
                        i = 4;
                        j = 4;
                        break;
                default:
                        i = 0;
                        j = 0;
                        break;
                }
                v4l2_info(sd, "\tNext carrier edge window:          16 clocks -%1d/+%1d, %u to %u Hz\n",
                          i, j,
                          clock_divider_to_freq(rxclk, 16 + j),
                          clock_divider_to_freq(rxclk, 16 - i));
        }
        v4l2_info(sd, "\tMax measurable pulse width:        %u us, %llu ns\n",
                  pulse_width_count_to_us(FIFO_RXTX, rxclk),
                  pulse_width_count_to_ns(FIFO_RXTX, rxclk));
        v4l2_info(sd, "\tLow pass filter:                   %s\n",
                  filtr ? "enabled" : "disabled");
        if (filtr)
                v4l2_info(sd, "\tMin acceptable pulse width (LPF):  %u us, %u ns\n",
                          lpf_count_to_us(filtr),
                          lpf_count_to_ns(filtr));
        v4l2_info(sd, "\tPulse width timer timed-out:       %s\n",
                  stats & STATS_RTO ? "yes" : "no");
        v4l2_info(sd, "\tPulse width timer time-out intr:   %s\n",
                  irqen & IRQEN_RTE ? "enabled" : "disabled");
        v4l2_info(sd, "\tFIFO overrun:                      %s\n",
                  stats & STATS_ROR ? "yes" : "no");
        v4l2_info(sd, "\tFIFO overrun interrupt:            %s\n",
                  irqen & IRQEN_ROE ? "enabled" : "disabled");
        v4l2_info(sd, "\tBusy:                              %s\n",
                  stats & STATS_RBY ? "yes" : "no");
        v4l2_info(sd, "\tFIFO service requested:            %s\n",
                  stats & STATS_RSR ? "yes" : "no");
        v4l2_info(sd, "\tFIFO service request interrupt:    %s\n",
                  irqen & IRQEN_RSE ? "enabled" : "disabled");

        v4l2_info(sd, "IR Transmitter:\n");
        v4l2_info(sd, "\tEnabled:                           %s\n",
                  cntrl & CNTRL_TXE ? "yes" : "no");
        v4l2_info(sd, "\tModulation onto a carrier:         %s\n",
                  cntrl & CNTRL_MOD ? "enabled" : "disabled");
        v4l2_info(sd, "\tFIFO:                              %s\n",
                  cntrl & CNTRL_TFE ? "enabled" : "disabled");
        v4l2_info(sd, "\tFIFO interrupt watermark:          %s\n",
                  cntrl & CNTRL_TIC ? "not empty" : "half full or less");
        v4l2_info(sd, "\tCarrier polarity:                  %s\n",
                  cntrl & CNTRL_CPL ? "space:burst mark:noburst"
                                    : "space:noburst mark:burst");
        if (cntrl & CNTRL_MOD) {
                v4l2_info(sd, "\tCarrier (16 clocks):               %u Hz\n",
                          clock_divider_to_carrier_freq(txclk));
                v4l2_info(sd, "\tCarrier duty cycle:                %2u/16\n",
                          cduty + 1);
        }
        v4l2_info(sd, "\tMax pulse width:                   %u us, %llu ns\n",
                  pulse_width_count_to_us(FIFO_RXTX, txclk),
                  pulse_width_count_to_ns(FIFO_RXTX, txclk));
        v4l2_info(sd, "\tBusy:                              %s\n",
                  stats & STATS_TBY ? "yes" : "no");
        v4l2_info(sd, "\tFIFO service requested:            %s\n",
                  stats & STATS_TSR ? "yes" : "no");
        v4l2_info(sd, "\tFIFO service request interrupt:    %s\n",
                  irqen & IRQEN_TSE ? "enabled" : "disabled");

        return 0;
}


const struct v4l2_subdev_ir_ops cx25840_ir_ops = {
        .rx_read = cx25840_ir_rx_read,
        .rx_g_parameters = cx25840_ir_rx_g_parameters,
        .rx_s_parameters = cx25840_ir_rx_s_parameters,

        .tx_write = cx25840_ir_tx_write,
        .tx_g_parameters = cx25840_ir_tx_g_parameters,
        .tx_s_parameters = cx25840_ir_tx_s_parameters,
};


static const struct v4l2_subdev_ir_parameters default_rx_params = {
        .bytes_per_data_element = sizeof(union cx25840_ir_fifo_rec),
        .mode = V4L2_SUBDEV_IR_MODE_PULSE_WIDTH,

        .enable = false,
        .interrupt_enable = false,
        .shutdown = true,

        .modulation = true,
        .carrier_freq = 36000, /* 36 kHz - RC-5, and RC-6 carrier */

        /* RC-5: 666,667 ns = 1/36 kHz * 32 cycles * 1 mark * 0.75 */
        /* RC-6: 333,333 ns = 1/36 kHz * 16 cycles * 1 mark * 0.75 */
        .noise_filter_min_width = 333333, /* ns */
        .carrier_range_lower = 35000,
        .carrier_range_upper = 37000,
        .invert_level = false,
};

static const struct v4l2_subdev_ir_parameters default_tx_params = {
        .bytes_per_data_element = sizeof(union cx25840_ir_fifo_rec),
        .mode = V4L2_SUBDEV_IR_MODE_PULSE_WIDTH,

        .enable = false,
        .interrupt_enable = false,
        .shutdown = true,

        .modulation = true,
        .carrier_freq = 36000, /* 36 kHz - RC-5 carrier */
        .duty_cycle = 25,      /* 25 %   - RC-5 carrier */
        .invert_level = false,
        .invert_carrier_sense = false,
};

int cx25840_ir_probe(struct v4l2_subdev *sd)
{
        struct cx25840_state *state = to_state(sd);
        struct cx25840_ir_state *ir_state;
        struct v4l2_subdev_ir_parameters default_params;

        /* Only init the IR controller for the CX2388[57] AV Core for now */
        if (!(is_cx23885(state) || is_cx23887(state)))
                return 0;

        ir_state = devm_kzalloc(&state->c->dev, sizeof(*ir_state), GFP_KERNEL);
        if (ir_state == NULL)
                return -ENOMEM;

        spin_lock_init(&ir_state->rx_kfifo_lock);
        if (kfifo_alloc(&ir_state->rx_kfifo,
                        CX25840_IR_RX_KFIFO_SIZE, GFP_KERNEL))
                return -ENOMEM;

        ir_state->c = state->c;
        state->ir_state = ir_state;

        /* Ensure no interrupts arrive yet */
        if (is_cx23885(state) || is_cx23887(state))
                cx25840_write4(ir_state->c, CX25840_IR_IRQEN_REG, IRQEN_MSK);
        else
                cx25840_write4(ir_state->c, CX25840_IR_IRQEN_REG, 0);

        mutex_init(&ir_state->rx_params_lock);
        default_params = default_rx_params;
        v4l2_subdev_call(sd, ir, rx_s_parameters, &default_params);

        mutex_init(&ir_state->tx_params_lock);
        default_params = default_tx_params;
        v4l2_subdev_call(sd, ir, tx_s_parameters, &default_params);

        return 0;
}

int cx25840_ir_remove(struct v4l2_subdev *sd)
{
        struct cx25840_state *state = to_state(sd);
        struct cx25840_ir_state *ir_state = to_ir_state(sd);

        if (ir_state == NULL)
                return -ENODEV;

        cx25840_ir_rx_shutdown(sd);
        cx25840_ir_tx_shutdown(sd);

        kfifo_free(&ir_state->rx_kfifo);
        state->ir_state = NULL;
        return 0;
}