/*
 * Amlogic Secure Monitor driver
 *
 * Copyright (C) 2016 Endless Mobile, Inc.
 * Author: Carlo Caione <carlo@endlessm.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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#define pr_fmt(fmt) "meson-sm: " fmt

#include <linux/arm-smccc.h>
#include <linux/bug.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/types.h>
#include <linux/sizes.h>
 #include <linux/slab.h>

#include <linux/firmware/meson/meson_sm.h>

struct meson_sm_cmd {
        unsigned int index;
        u32 smc_id;
};
#define CMD(d, s) { .index = (d), .smc_id = (s), }

struct meson_sm_chip {
        unsigned int shmem_size;
        u32 cmd_shmem_in_base;
        u32 cmd_shmem_out_base;
        struct meson_sm_cmd cmd[];
};

struct meson_sm_chip gxbb_chip = {
        .shmem_size             = SZ_4K,
        .cmd_shmem_in_base      = 0x82000020,
        .cmd_shmem_out_base     = 0x82000021,
        .cmd = {
                CMD(SM_EFUSE_READ,      0x82000030),
                CMD(SM_EFUSE_WRITE,     0x82000031),
                CMD(SM_EFUSE_USER_MAX,  0x82000033),
                CMD(SM_GET_CHIP_ID,     0x82000044),
                { /* sentinel */ },
        },
};

struct meson_sm_firmware {
        const struct meson_sm_chip *chip;
        void __iomem *sm_shmem_in_base;
        void __iomem *sm_shmem_out_base;
};

static struct meson_sm_firmware fw;

static u32 meson_sm_get_cmd(const struct meson_sm_chip *chip,
                            unsigned int cmd_index)
{
        const struct meson_sm_cmd *cmd = chip->cmd;

        while (cmd->smc_id && cmd->index != cmd_index)
                cmd++;

        return cmd->smc_id;
}

static u32 __meson_sm_call(u32 cmd, u32 arg0, u32 arg1, u32 arg2,
                           u32 arg3, u32 arg4)
{
        struct arm_smccc_res res;

        arm_smccc_smc(cmd, arg0, arg1, arg2, arg3, arg4, 0, 0, &res);
        return res.a0;
}

static void __iomem *meson_sm_map_shmem(u32 cmd_shmem, unsigned int size)
{
        u32 sm_phy_base;

        sm_phy_base = __meson_sm_call(cmd_shmem, 0, 0, 0, 0, 0);
        if (!sm_phy_base)
                return 0;

        return ioremap_cache(sm_phy_base, size);
}

/**
 * meson_sm_call - generic SMC32 call to the secure-monitor
 *
 * @cmd_index:  Index of the SMC32 function ID
 * @ret:        Returned value
 * @arg0:       SMC32 Argument 0
 * @arg1:       SMC32 Argument 1
 * @arg2:       SMC32 Argument 2
 * @arg3:       SMC32 Argument 3
 * @arg4:       SMC32 Argument 4
 *
 * Return:      0 on success, a negative value on error
 */
int meson_sm_call(unsigned int cmd_index, u32 *ret, u32 arg0,
                  u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
        u32 cmd, lret;

        if (!fw.chip)
                return -ENOENT;

        cmd = meson_sm_get_cmd(fw.chip, cmd_index);
        if (!cmd)
                return -EINVAL;

        lret = __meson_sm_call(cmd, arg0, arg1, arg2, arg3, arg4);

        if (ret)
                *ret = lret;

        return 0;
}
EXPORT_SYMBOL(meson_sm_call);

/**
 * meson_sm_call_read - retrieve data from secure-monitor
 *
 * @buffer:     Buffer to store the retrieved data
 * @bsize:      Size of the buffer
 * @cmd_index:  Index of the SMC32 function ID
 * @arg0:       SMC32 Argument 0
 * @arg1:       SMC32 Argument 1
 * @arg2:       SMC32 Argument 2
 * @arg3:       SMC32 Argument 3
 * @arg4:       SMC32 Argument 4
 *
 * Return:      size of read data on success, a negative value on error
 *              When 0 is returned there is no guarantee about the amount of
 *              data read and bsize bytes are copied in buffer.
 */
int meson_sm_call_read(void *buffer, unsigned int bsize, unsigned int cmd_index,
                       u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
        u32 size;
        int ret;

        if (!fw.chip)
                return -ENOENT;

        if (!fw.chip->cmd_shmem_out_base)
                return -EINVAL;

        if (bsize > fw.chip->shmem_size)
                return -EINVAL;

        if (meson_sm_call(cmd_index, &size, arg0, arg1, arg2, arg3, arg4) < 0)
                return -EINVAL;

        if (size > bsize)
                return -EINVAL;

        ret = size;

        if (!size)
                size = bsize;

        if (buffer)
                memcpy(buffer, fw.sm_shmem_out_base, size);

        return ret;
}
EXPORT_SYMBOL(meson_sm_call_read);

/**
 * meson_sm_call_write - send data to secure-monitor
 *
 * @buffer:     Buffer containing data to send
 * @size:       Size of the data to send
 * @cmd_index:  Index of the SMC32 function ID
 * @arg0:       SMC32 Argument 0
 * @arg1:       SMC32 Argument 1
 * @arg2:       SMC32 Argument 2
 * @arg3:       SMC32 Argument 3
 * @arg4:       SMC32 Argument 4
 *
 * Return:      size of sent data on success, a negative value on error
 */
int meson_sm_call_write(void *buffer, unsigned int size, unsigned int cmd_index,
                        u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
        u32 written;

        if (!fw.chip)
                return -ENOENT;

        if (size > fw.chip->shmem_size)
                return -EINVAL;

        if (!fw.chip->cmd_shmem_in_base)
                return -EINVAL;

        memcpy(fw.sm_shmem_in_base, buffer, size);

        if (meson_sm_call(cmd_index, &written, arg0, arg1, arg2, arg3, arg4) < 0)
                return -EINVAL;

        if (!written)
                return -EINVAL;

        return written;
}
EXPORT_SYMBOL(meson_sm_call_write);

#define SM_CHIP_ID_LENGTH       119
#define SM_CHIP_ID_OFFSET       4
#define SM_CHIP_ID_SIZE         12

static ssize_t serial_show(struct device *dev, struct device_attribute *attr,
                         char *buf)
{
        uint8_t *id_buf;
        int ret;

        id_buf = kmalloc(SM_CHIP_ID_LENGTH, GFP_KERNEL);
        if (!id_buf)
                return -ENOMEM;

        ret = meson_sm_call_read(id_buf, SM_CHIP_ID_LENGTH, SM_GET_CHIP_ID,
                                 0, 0, 0, 0, 0);
        if (ret < 0) {
                kfree(id_buf);
                return ret;
        }

        ret = sprintf(buf, "%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n",
                        id_buf[SM_CHIP_ID_OFFSET + 0],
                        id_buf[SM_CHIP_ID_OFFSET + 1],
                        id_buf[SM_CHIP_ID_OFFSET + 2],
                        id_buf[SM_CHIP_ID_OFFSET + 3],
                        id_buf[SM_CHIP_ID_OFFSET + 4],
                        id_buf[SM_CHIP_ID_OFFSET + 5],
                        id_buf[SM_CHIP_ID_OFFSET + 6],
                        id_buf[SM_CHIP_ID_OFFSET + 7],
                        id_buf[SM_CHIP_ID_OFFSET + 8],
                        id_buf[SM_CHIP_ID_OFFSET + 9],
                        id_buf[SM_CHIP_ID_OFFSET + 10],
                        id_buf[SM_CHIP_ID_OFFSET + 11]);

        kfree(id_buf);

        return ret;
}

static DEVICE_ATTR_RO(serial);

static struct attribute *meson_sm_sysfs_attributes[] = {
        &dev_attr_serial.attr,
        NULL,
};

static const struct attribute_group meson_sm_sysfs_attr_group = {
        .attrs = meson_sm_sysfs_attributes,
};

static const struct of_device_id meson_sm_ids[] = {
        { .compatible = "amlogic,meson-gxbb-sm", .data = &gxbb_chip },
        { /* sentinel */ },
};

static int __init meson_sm_probe(struct platform_device *pdev)
{
        const struct meson_sm_chip *chip;

        chip = of_match_device(meson_sm_ids, &pdev->dev)->data;

        if (chip->cmd_shmem_in_base) {
                fw.sm_shmem_in_base = meson_sm_map_shmem(chip->cmd_shmem_in_base,
                                                         chip->shmem_size);
                if (WARN_ON(!fw.sm_shmem_in_base))
                        goto out;
        }

        if (chip->cmd_shmem_out_base) {
                fw.sm_shmem_out_base = meson_sm_map_shmem(chip->cmd_shmem_out_base,
                                                          chip->shmem_size);
                if (WARN_ON(!fw.sm_shmem_out_base))
                        goto out_in_base;
        }

        fw.chip = chip;
        pr_info("secure-monitor enabled\n");

        if (sysfs_create_group(&pdev->dev.kobj, &meson_sm_sysfs_attr_group))
                goto out_in_base;

        return 0;

out_in_base:
        iounmap(fw.sm_shmem_in_base);
out:
        return -EINVAL;
}

static struct platform_driver meson_sm_driver = {
        .driver = {
                .name = "meson-sm",
                .of_match_table = of_match_ptr(meson_sm_ids),
        },
};
module_platform_driver_probe(meson_sm_driver, meson_sm_probe);