/*
 * CCI cache coherent interconnect driver
 *
 * Copyright (C) 2013 ARM Ltd.
 * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/arm-cci.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/slab.h>

#include <asm/cacheflush.h>
#include <asm/smp_plat.h>

#define CCI_PORT_CTRL           0x0
#define CCI_CTRL_STATUS         0xc

#define CCI_ENABLE_SNOOP_REQ    0x1
#define CCI_ENABLE_DVM_REQ      0x2
#define CCI_ENABLE_REQ          (CCI_ENABLE_SNOOP_REQ | CCI_ENABLE_DVM_REQ)

struct cci_nb_ports {
        unsigned int nb_ace;
        unsigned int nb_ace_lite;
};

enum cci_ace_port_type {
        ACE_INVALID_PORT = 0x0,
        ACE_PORT,
        ACE_LITE_PORT,
};

struct cci_ace_port {
        void __iomem *base;
        unsigned long phys;
        enum cci_ace_port_type type;
        struct device_node *dn;
};

static struct cci_ace_port *ports;
static unsigned int nb_cci_ports;

static void __iomem *cci_ctrl_base;
static unsigned long cci_ctrl_phys;

struct cpu_port {
        u64 mpidr;
        u32 port;
};

/*
 * Use the port MSB as valid flag, shift can be made dynamic
 * by computing number of bits required for port indexes.
 * Code disabling CCI cpu ports runs with D-cache invalidated
 * and SCTLR bit clear so data accesses must be kept to a minimum
 * to improve performance; for now shift is left static to
 * avoid one more data access while disabling the CCI port.
 */
#define PORT_VALID_SHIFT        31
#define PORT_VALID              (0x1 << PORT_VALID_SHIFT)

static inline void init_cpu_port(struct cpu_port *port, u32 index, u64 mpidr)
{
        port->port = PORT_VALID | index;
        port->mpidr = mpidr;
}

static inline bool cpu_port_is_valid(struct cpu_port *port)
{
        return !!(port->port & PORT_VALID);
}

static inline bool cpu_port_match(struct cpu_port *port, u64 mpidr)
{
        return port->mpidr == (mpidr & MPIDR_HWID_BITMASK);
}

static struct cpu_port cpu_port[NR_CPUS];

/**
 * __cci_ace_get_port - Function to retrieve the port index connected to
 *                      a cpu or device.
 *
 * @dn: device node of the device to look-up
 * @type: port type
 *
 * Return value:
 *      - CCI port index if success
 *      - -ENODEV if failure
 */
static int __cci_ace_get_port(struct device_node *dn, int type)
{
        int i;
        bool ace_match;
        struct device_node *cci_portn;

        cci_portn = of_parse_phandle(dn, "cci-control-port", 0);
        for (i = 0; i < nb_cci_ports; i++) {
                ace_match = ports[i].type == type;
                if (ace_match && cci_portn == ports[i].dn)
                        return i;
        }
        return -ENODEV;
}

int cci_ace_get_port(struct device_node *dn)
{
        return __cci_ace_get_port(dn, ACE_LITE_PORT);
}
EXPORT_SYMBOL_GPL(cci_ace_get_port);

static void __init cci_ace_init_ports(void)
{
        int port, cpu;
        struct device_node *cpun;

        /*
         * Port index look-up speeds up the function disabling ports by CPU,
         * since the logical to port index mapping is done once and does
         * not change after system boot.
         * The stashed index array is initialized for all possible CPUs
         * at probe time.
         */
        for_each_possible_cpu(cpu) {
                /* too early to use cpu->of_node */
                cpun = of_get_cpu_node(cpu, NULL);

                if (WARN(!cpun, "Missing cpu device node\n"))
                        continue;

                port = __cci_ace_get_port(cpun, ACE_PORT);
                if (port < 0)
                        continue;

                init_cpu_port(&cpu_port[cpu], port, cpu_logical_map(cpu));
        }

        for_each_possible_cpu(cpu) {
                WARN(!cpu_port_is_valid(&cpu_port[cpu]),
                        "CPU %u does not have an associated CCI port\n",
                        cpu);
        }
}
/*
 * Functions to enable/disable a CCI interconnect slave port
 *
 * They are called by low-level power management code to disable slave
 * interfaces snoops and DVM broadcast.
 * Since they may execute with cache data allocation disabled and
 * after the caches have been cleaned and invalidated the functions provide
 * no explicit locking since they may run with D-cache disabled, so normal
 * cacheable kernel locks based on ldrex/strex may not work.
 * Locking has to be provided by BSP implementations to ensure proper
 * operations.
 */

/**
 * cci_port_control() - function to control a CCI port
 *
 * @port: index of the port to setup
 * @enable: if true enables the port, if false disables it
 */
static void notrace cci_port_control(unsigned int port, bool enable)
{
        void __iomem *base = ports[port].base;

        writel_relaxed(enable ? CCI_ENABLE_REQ : 0, base + CCI_PORT_CTRL);
        /*
         * This function is called from power down procedures
         * and must not execute any instruction that might
         * cause the processor to be put in a quiescent state
         * (eg wfi). Hence, cpu_relax() can not be added to this
         * read loop to optimize power, since it might hide possibly
         * disruptive operations.
         */
        while (readl_relaxed(cci_ctrl_base + CCI_CTRL_STATUS) & 0x1)
                        ;
}

/**
 * cci_disable_port_by_cpu() - function to disable a CCI port by CPU
 *                             reference
 *
 * @mpidr: mpidr of the CPU whose CCI port should be disabled
 *
 * Disabling a CCI port for a CPU implies disabling the CCI port
 * controlling that CPU cluster. Code disabling CPU CCI ports
 * must make sure that the CPU running the code is the last active CPU
 * in the cluster ie all other CPUs are quiescent in a low power state.
 *
 * Return:
 *      0 on success
 *      -ENODEV on port look-up failure
 */
int notrace cci_disable_port_by_cpu(u64 mpidr)
{
        int cpu;
        bool is_valid;
        for (cpu = 0; cpu < nr_cpu_ids; cpu++) {
                is_valid = cpu_port_is_valid(&cpu_port[cpu]);
                if (is_valid && cpu_port_match(&cpu_port[cpu], mpidr)) {
                        cci_port_control(cpu_port[cpu].port, false);
                        return 0;
                }
        }
        return -ENODEV;
}
EXPORT_SYMBOL_GPL(cci_disable_port_by_cpu);

/**
 * cci_enable_port_for_self() - enable a CCI port for calling CPU
 *
 * Enabling a CCI port for the calling CPU implies enabling the CCI
 * port controlling that CPU's cluster. Caller must make sure that the
 * CPU running the code is the first active CPU in the cluster and all
 * other CPUs are quiescent in a low power state  or waiting for this CPU
 * to complete the CCI initialization.
 *
 * Because this is called when the MMU is still off and with no stack,
 * the code must be position independent and ideally rely on callee
 * clobbered registers only.  To achieve this we must code this function
 * entirely in assembler.
 *
 * On success this returns with the proper CCI port enabled.  In case of
 * any failure this never returns as the inability to enable the CCI is
 * fatal and there is no possible recovery at this stage.
 */
asmlinkage void __naked cci_enable_port_for_self(void)
{
        asm volatile ("\n"
"       .arch armv7-a\n"
"       mrc     p15, 0, r0, c0, c0, 5   @ get MPIDR value \n"
"       and     r0, r0, #"__stringify(MPIDR_HWID_BITMASK)" \n"
"       adr     r1, 5f \n"
"       ldr     r2, [r1] \n"
"       add     r1, r1, r2              @ &cpu_port \n"
"       add     ip, r1, %[sizeof_cpu_port] \n"

        /* Loop over the cpu_port array looking for a matching MPIDR */
"1:     ldr     r2, [r1, %[offsetof_cpu_port_mpidr_lsb]] \n"
"       cmp     r2, r0                  @ compare MPIDR \n"
"       bne     2f \n"

        /* Found a match, now test port validity */
"       ldr     r3, [r1, %[offsetof_cpu_port_port]] \n"
"       tst     r3, #"__stringify(PORT_VALID)" \n"
"       bne     3f \n"

        /* no match, loop with the next cpu_port entry */
"2:     add     r1, r1, %[sizeof_struct_cpu_port] \n"
"       cmp     r1, ip                  @ done? \n"
"       blo     1b \n"

        /* CCI port not found -- cheaply try to stall this CPU */
"cci_port_not_found: \n"
"       wfi \n"
"       wfe \n"
"       b       cci_port_not_found \n"

        /* Use matched port index to look up the corresponding ports entry */
"3:     bic     r3, r3, #"__stringify(PORT_VALID)" \n"
"       adr     r0, 6f \n"
"       ldmia   r0, {r1, r2} \n"
"       sub     r1, r1, r0              @ virt - phys \n"
"       ldr     r0, [r0, r2]            @ *(&ports) \n"
"       mov     r2, %[sizeof_struct_ace_port] \n"
"       mla     r0, r2, r3, r0          @ &ports[index] \n"
"       sub     r0, r0, r1              @ virt_to_phys() \n"

        /* Enable the CCI port */
"       ldr     r0, [r0, %[offsetof_port_phys]] \n"
"       mov     r3, #"__stringify(CCI_ENABLE_REQ)" \n"
"       str     r3, [r0, #"__stringify(CCI_PORT_CTRL)"] \n"

        /* poll the status reg for completion */
"       adr     r1, 7f \n"
"       ldr     r0, [r1] \n"
"       ldr     r0, [r0, r1]            @ cci_ctrl_base \n"
"4:     ldr     r1, [r0, #"__stringify(CCI_CTRL_STATUS)"] \n"
"       tst     r1, #1 \n"
"       bne     4b \n"

"       mov     r0, #0 \n"
"       bx      lr \n"

"       .align  2 \n"
"5:     .word   cpu_port - . \n"
"6:     .word   . \n"
"       .word   ports - 6b \n"
"7:     .word   cci_ctrl_phys - . \n"
        : :
        [sizeof_cpu_port] "i" (sizeof(cpu_port)),
#ifndef __ARMEB__
        [offsetof_cpu_port_mpidr_lsb] "i" (offsetof(struct cpu_port, mpidr)),
#else
        [offsetof_cpu_port_mpidr_lsb] "i" (offsetof(struct cpu_port, mpidr)+4),
#endif
        [offsetof_cpu_port_port] "i" (offsetof(struct cpu_port, port)),
        [sizeof_struct_cpu_port] "i" (sizeof(struct cpu_port)),
        [sizeof_struct_ace_port] "i" (sizeof(struct cci_ace_port)),
        [offsetof_port_phys] "i" (offsetof(struct cci_ace_port, phys)) );

        unreachable();
}

/**
 * __cci_control_port_by_device() - function to control a CCI port by device
 *                                  reference
 *
 * @dn: device node pointer of the device whose CCI port should be
 *      controlled
 * @enable: if true enables the port, if false disables it
 *
 * Return:
 *      0 on success
 *      -ENODEV on port look-up failure
 */
int notrace __cci_control_port_by_device(struct device_node *dn, bool enable)
{
        int port;

        if (!dn)
                return -ENODEV;

        port = __cci_ace_get_port(dn, ACE_LITE_PORT);
        if (WARN_ONCE(port < 0, "node %s ACE lite port look-up failure\n",
                                dn->full_name))
                return -ENODEV;
        cci_port_control(port, enable);
        return 0;
}
EXPORT_SYMBOL_GPL(__cci_control_port_by_device);

/**
 * __cci_control_port_by_index() - function to control a CCI port by port index
 *
 * @port: port index previously retrieved with cci_ace_get_port()
 * @enable: if true enables the port, if false disables it
 *
 * Return:
 *      0 on success
 *      -ENODEV on port index out of range
 *      -EPERM if operation carried out on an ACE PORT
 */
int notrace __cci_control_port_by_index(u32 port, bool enable)
{
        if (port >= nb_cci_ports || ports[port].type == ACE_INVALID_PORT)
                return -ENODEV;
        /*
         * CCI control for ports connected to CPUS is extremely fragile
         * and must be made to go through a specific and controlled
         * interface (ie cci_disable_port_by_cpu(); control by general purpose
         * indexing is therefore disabled for ACE ports.
         */
        if (ports[port].type == ACE_PORT)
                return -EPERM;

        cci_port_control(port, enable);
        return 0;
}
EXPORT_SYMBOL_GPL(__cci_control_port_by_index);

static const struct cci_nb_ports cci400_ports = {
        .nb_ace = 2,
        .nb_ace_lite = 3
};

static const struct of_device_id arm_cci_matches[] = {
        {.compatible = "arm,cci-400", .data = &cci400_ports },
        {},
};

static const struct of_device_id arm_cci_ctrl_if_matches[] = {
        {.compatible = "arm,cci-400-ctrl-if", },
        {},
};

static int __init cci_probe(void)
{
        struct cci_nb_ports const *cci_config;
        int ret, i, nb_ace = 0, nb_ace_lite = 0;
        struct device_node *np, *cp;
        struct resource res;
        const char *match_str;
        bool is_ace;

        np = of_find_matching_node(NULL, arm_cci_matches);
        if (!np)
                return -ENODEV;

        cci_config = of_match_node(arm_cci_matches, np)->data;
        if (!cci_config)
                return -ENODEV;

        nb_cci_ports = cci_config->nb_ace + cci_config->nb_ace_lite;

        ports = kcalloc(sizeof(*ports), nb_cci_ports, GFP_KERNEL);
        if (!ports)
                return -ENOMEM;

        ret = of_address_to_resource(np, 0, &res);
        if (!ret) {
                cci_ctrl_base = ioremap(res.start, resource_size(&res));
                cci_ctrl_phys = res.start;
        }
        if (ret || !cci_ctrl_base) {
                WARN(1, "unable to ioremap CCI ctrl\n");
                ret = -ENXIO;
                goto memalloc_err;
        }

        for_each_child_of_node(np, cp) {
                if (!of_match_node(arm_cci_ctrl_if_matches, cp))
                        continue;

                i = nb_ace + nb_ace_lite;

                if (i >= nb_cci_ports)
                        break;

                if (of_property_read_string(cp, "interface-type",
                                        &match_str)) {
                        WARN(1, "node %s missing interface-type property\n",
                                  cp->full_name);
                        continue;
                }
                is_ace = strcmp(match_str, "ace") == 0;
                if (!is_ace && strcmp(match_str, "ace-lite")) {
                        WARN(1, "node %s containing invalid interface-type property, skipping it\n",
                                        cp->full_name);
                        continue;
                }

                ret = of_address_to_resource(cp, 0, &res);
                if (!ret) {
                        ports[i].base = ioremap(res.start, resource_size(&res));
                        ports[i].phys = res.start;
                }
                if (ret || !ports[i].base) {
                        WARN(1, "unable to ioremap CCI port %d\n", i);
                        continue;
                }

                if (is_ace) {
                        if (WARN_ON(nb_ace >= cci_config->nb_ace))
                                continue;
                        ports[i].type = ACE_PORT;
                        ++nb_ace;
                } else {
                        if (WARN_ON(nb_ace_lite >= cci_config->nb_ace_lite))
                                continue;
                        ports[i].type = ACE_LITE_PORT;
                        ++nb_ace_lite;
                }
                ports[i].dn = cp;
        }

         /* initialize a stashed array of ACE ports to speed-up look-up */
        cci_ace_init_ports();

        /*
         * Multi-cluster systems may need this data when non-coherent, during
         * cluster power-up/power-down. Make sure it reaches main memory.
         */
        sync_cache_w(&cci_ctrl_base);
        sync_cache_w(&cci_ctrl_phys);
        sync_cache_w(&ports);
        sync_cache_w(&cpu_port);
        __sync_cache_range_w(ports, sizeof(*ports) * nb_cci_ports);
        pr_info("ARM CCI driver probed\n");
        return 0;

memalloc_err:

        kfree(ports);
        return ret;
}

static int cci_init_status = -EAGAIN;
static DEFINE_MUTEX(cci_probing);

static int __init cci_init(void)
{
        if (cci_init_status != -EAGAIN)
                return cci_init_status;

        mutex_lock(&cci_probing);
        if (cci_init_status == -EAGAIN)
                cci_init_status = cci_probe();
        mutex_unlock(&cci_probing);
        return cci_init_status;
}

/*
 * To sort out early init calls ordering a helper function is provided to
 * check if the CCI driver has beed initialized. Function check if the driver
 * has been initialized, if not it calls the init function that probes
 * the driver and updates the return value.
 */
bool __init cci_probed(void)
{
        return cci_init() == 0;
}
EXPORT_SYMBOL_GPL(cci_probed);

early_initcall(cci_init);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ARM CCI support");