/*
 * Xilinx SPI driver
 *
 * supports 8 bit SPI transfers only, with or w/o FIFO
 *
 * based on bfin_spi.c, by way of altera_spi.c
 * Copyright (c) 2005-2008 Analog Devices Inc.
 * Copyright (c) 2010 Thomas Chou <thomas@wytron.com.tw>
 * Copyright (c) 2010 Graeme Smecher <graeme.smecher@mail.mcgill.ca>
 * Copyright (c) 2012 Stephan Linz <linz@li-pro.net>
 *
 * Licensed under the GPL-2 or later.
 *
 * [0]: http://www.xilinx.com/support/documentation
 *
 * [S]: [0]/ip_documentation/xps_spi.pdf
 *      [0]/ip_documentation/axi_spi_ds742.pdf
 */
#include <config.h>
#include <common.h>
#include <malloc.h>
#include <spi.h>

#include "xilinx_spi.h"

#ifndef CONFIG_SYS_XILINX_SPI_LIST
#define CONFIG_SYS_XILINX_SPI_LIST      { CONFIG_SYS_SPI_BASE }
#endif

#ifndef CONFIG_XILINX_SPI_IDLE_VAL
#define CONFIG_XILINX_SPI_IDLE_VAL      0xff
#endif

#define XILSPI_SPICR_DFLT_ON            (SPICR_MANUAL_SS | \
                                         SPICR_MASTER_MODE | \
                                         SPICR_SPE)

#define XILSPI_SPICR_DFLT_OFF           (SPICR_MASTER_INHIBIT | \
                                         SPICR_MANUAL_SS)

#define XILSPI_MAX_XFER_BITS            8

static unsigned long xilinx_spi_base_list[] = CONFIG_SYS_XILINX_SPI_LIST;

__attribute__((weak))
int spi_cs_is_valid(unsigned int bus, unsigned int cs)
{
        return bus < ARRAY_SIZE(xilinx_spi_base_list) && cs < 32;
}

__attribute__((weak))
void spi_cs_activate(struct spi_slave *slave)
{
        struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);

        writel(SPISSR_ACT(slave->cs), &xilspi->regs->spissr);
}

__attribute__((weak))
void spi_cs_deactivate(struct spi_slave *slave)
{
        struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);

        writel(SPISSR_OFF, &xilspi->regs->spissr);
}

void spi_init(void)
{
        /* do nothing */
}

void spi_set_speed(struct spi_slave *slave, uint hz)
{
        /* xilinx spi core does not support programmable speed */
}

struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
                                  unsigned int max_hz, unsigned int mode)
{
        struct xilinx_spi_slave *xilspi;

        if (!spi_cs_is_valid(bus, cs)) {
                printf("XILSPI error: %s: unsupported bus %d / cs %d\n",
                                __func__, bus, cs);
                return NULL;
        }

        xilspi = malloc(sizeof(*xilspi));
        if (!xilspi) {
                printf("XILSPI error: %s: malloc of SPI structure failed\n",
                                __func__);
                return NULL;
        }
        xilspi->slave.bus = bus;
        xilspi->slave.cs = cs;
        xilspi->regs = (struct xilinx_spi_reg *)xilinx_spi_base_list[bus];
        xilspi->freq = max_hz;
        xilspi->mode = mode;
        debug("%s: bus:%i cs:%i base:%p mode:%x max_hz:%d\n", __func__,
                bus, cs, xilspi->regs, xilspi->mode, xilspi->freq);

        return &xilspi->slave;
}

void spi_free_slave(struct spi_slave *slave)
{
        struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);

        free(xilspi);
}

int spi_claim_bus(struct spi_slave *slave)
{
        struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
        u32 spicr;

        debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
        writel(SPISSR_OFF, &xilspi->regs->spissr);

        spicr = XILSPI_SPICR_DFLT_ON;
        if (xilspi->mode & SPI_LSB_FIRST)
                spicr |= SPICR_LSB_FIRST;
        if (xilspi->mode & SPI_CPHA)
                spicr |= SPICR_CPHA;
        if (xilspi->mode & SPI_CPOL)
                spicr |= SPICR_CPOL;
        if (xilspi->mode & SPI_LOOP)
                spicr |= SPICR_LOOP;

        writel(spicr, &xilspi->regs->spicr);
        return 0;
}

void spi_release_bus(struct spi_slave *slave)
{
        struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);

        debug("%s: bus:%i cs:%i\n", __func__, slave->bus, slave->cs);
        writel(SPISSR_OFF, &xilspi->regs->spissr);
        writel(XILSPI_SPICR_DFLT_OFF, &xilspi->regs->spicr);
}

int spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
             void *din, unsigned long flags)
{
        struct xilinx_spi_slave *xilspi = to_xilinx_spi_slave(slave);
        /* assume spi core configured to do 8 bit transfers */
        unsigned int bytes = bitlen / XILSPI_MAX_XFER_BITS;
        const unsigned char *txp = dout;
        unsigned char *rxp = din;
        unsigned rxecount = 17; /* max. 16 elements in FIFO, leftover 1 */

        debug("%s: bus:%i cs:%i bitlen:%i bytes:%i flags:%lx\n", __func__,
                slave->bus, slave->cs, bitlen, bytes, flags);
        if (bitlen == 0)
                goto done;

        if (bitlen % XILSPI_MAX_XFER_BITS) {
                printf("XILSPI warning: %s: Not a multiple of %d bits\n",
                                __func__, XILSPI_MAX_XFER_BITS);
                flags |= SPI_XFER_END;
                goto done;
        }

        /* empty read buffer */
        while (rxecount && !(readl(&xilspi->regs->spisr) & SPISR_RX_EMPTY)) {
                readl(&xilspi->regs->spidrr);
                rxecount--;
        }

        if (!rxecount) {
                printf("XILSPI error: %s: Rx buffer not empty\n", __func__);
                return -1;
        }

        if (flags & SPI_XFER_BEGIN)
                spi_cs_activate(slave);

        while (bytes--) {
                unsigned timeout = /* at least 1usec or greater, leftover 1 */
                        xilspi->freq > XILSPI_MAX_XFER_BITS * 1000000 ? 2 :
                        (XILSPI_MAX_XFER_BITS * 1000000 / xilspi->freq) + 1;

                /* get Tx element from data out buffer and count up */
                unsigned char d = txp ? *txp++ : CONFIG_XILINX_SPI_IDLE_VAL;
                debug("%s: tx:%x ", __func__, d);

                /* write out and wait for processing (receive data) */
                writel(d & SPIDTR_8BIT_MASK, &xilspi->regs->spidtr);
                while (timeout && readl(&xilspi->regs->spisr)
                                                & SPISR_RX_EMPTY) {
                        timeout--;
                        udelay(1);
                }

                if (!timeout) {
                        printf("XILSPI error: %s: Xfer timeout\n", __func__);
                        return -1;
                }

                /* read Rx element and push into data in buffer */
                d = readl(&xilspi->regs->spidrr) & SPIDRR_8BIT_MASK;
                if (rxp)
                        *rxp++ = d;
                debug("rx:%x\n", d);
        }

 done:
        if (flags & SPI_XFER_END)
                spi_cs_deactivate(slave);

        return 0;
}