// SPDX-License-Identifier: GPL-2.0-only
/*
 * Amlogic Secure Monitor driver
 *
 * Copyright (C) 2016 Endless Mobile, Inc.
 * Author: Carlo Caione <carlo@endlessm.com>
 */

#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_platform.h>
#include <linux/platform_device.h>
#include <linux/printk.h>
#include <linux/property.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[];
};

static const 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),
                CMD(SM_A1_PWRC_SET,     0x82000093),
                CMD(SM_A1_PWRC_GET,     0x82000095),
                { /* sentinel */ },
        },
};

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

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 s32 __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 NULL;

        return ioremap_cache(sm_phy_base, size);
}

/**
 * meson_sm_call - generic SMC32 call to the secure-monitor
 *
 * @fw:         Pointer to secure-monitor firmware
 * @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(struct meson_sm_firmware *fw, unsigned int cmd_index,
                  s32 *ret, u32 arg0, u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
        u32 cmd;
        s32 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
 *
 * @fw:         Pointer to secure-monitor firmware
 * @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(struct meson_sm_firmware *fw, void *buffer,
                       unsigned int bsize, unsigned int cmd_index, u32 arg0,
                       u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
        s32 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(fw, cmd_index, &size, arg0, arg1, arg2, arg3, arg4) < 0)
                return -EINVAL;

        if (size < 0 || size > bsize)
                return -EINVAL;

        ret = size;

        /* In some cases (for example GET_CHIP_ID command),
         * SMC doesn't return the number of bytes read, even
         * though the bytes were actually read into sm_shmem_out.
         * So this check is needed.
         */
        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
 *
 * @fw:         Pointer to secure-monitor firmware
 * @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(struct meson_sm_firmware *fw, void *buffer,
                        unsigned int size, unsigned int cmd_index, u32 arg0,
                        u32 arg1, u32 arg2, u32 arg3, u32 arg4)
{
        s32 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(fw, cmd_index, &written, arg0, arg1, arg2, arg3, arg4) < 0)
                return -EINVAL;

        if (written <= 0 || written > size)
                return -EINVAL;

        return written;
}
EXPORT_SYMBOL(meson_sm_call_write);

/**
 * meson_sm_get - get pointer to meson_sm_firmware structure.
 *
 * @sm_node:            Pointer to the secure-monitor Device Tree node.
 *
 * Return:              NULL is the secure-monitor device is not ready.
 */
struct meson_sm_firmware *meson_sm_get(struct device_node *sm_node)
{
        struct platform_device *pdev = of_find_device_by_node(sm_node);
        struct meson_sm_firmware *fw;

        if (!pdev)
                return NULL;

        fw = platform_get_drvdata(pdev);

        put_device(&pdev->dev);

        return fw;
}
EXPORT_SYMBOL_GPL(meson_sm_get);

#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)
{
        struct platform_device *pdev = to_platform_device(dev);
        struct meson_sm_firmware *fw;
        uint8_t *id_buf;
        int ret;

        fw = platform_get_drvdata(pdev);

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

        ret = meson_sm_call_read(fw, 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, "%12phN\n", &id_buf[SM_CHIP_ID_OFFSET]);

        kfree(id_buf);

        return ret;
}

static DEVICE_ATTR_RO(serial);

static struct attribute *meson_sm_sysfs_attrs[] = {
        &dev_attr_serial.attr,
        NULL,
};
ATTRIBUTE_GROUPS(meson_sm_sysfs);

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)
{
        struct device *dev = &pdev->dev;
        const struct meson_sm_chip *chip;
        struct meson_sm_firmware *fw;

        fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL);
        if (!fw)
                return -ENOMEM;

        chip = device_get_match_data(dev);
        if (!chip)
                return -EINVAL;

        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 unmap_in_base;
        }

        fw->chip = chip;

        platform_set_drvdata(pdev, fw);

        if (devm_of_platform_populate(dev))
                goto unmap_out_base;

        pr_info("secure-monitor enabled\n");

        return 0;

unmap_out_base:
        iounmap(fw->sm_shmem_out_base);
unmap_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),
                .dev_groups = meson_sm_sysfs_groups,
        },
};
module_platform_driver_probe(meson_sm_driver, meson_sm_probe);
MODULE_DESCRIPTION("Amlogic Secure Monitor driver");
MODULE_LICENSE("GPL v2");