// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2020 Arm Limited
 */

#define pr_fmt(fmt) "SMCCC: SOC_ID: " fmt

#include <linux/arm-smccc.h>
#include <linux/bitfield.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sys_soc.h>

#define SMCCC_SOC_ID_JEP106_BANK_IDX_MASK       GENMASK(30, 24)
/*
 * As per the SMC Calling Convention specification v1.2 (ARM DEN 0028C)
 * Section 7.4 SMCCC_ARCH_SOC_ID bits[23:16] are JEP-106 identification
 * code with parity bit for the SiP. We can drop the parity bit.
 */
#define SMCCC_SOC_ID_JEP106_ID_CODE_MASK        GENMASK(22, 16)
#define SMCCC_SOC_ID_IMP_DEF_SOC_ID_MASK        GENMASK(15, 0)

#define JEP106_BANK_CONT_CODE(x)        \
        (u8)(FIELD_GET(SMCCC_SOC_ID_JEP106_BANK_IDX_MASK, (x)))
#define JEP106_ID_CODE(x)       \
        (u8)(FIELD_GET(SMCCC_SOC_ID_JEP106_ID_CODE_MASK, (x)))
#define IMP_DEF_SOC_ID(x)       \
        (u16)(FIELD_GET(SMCCC_SOC_ID_IMP_DEF_SOC_ID_MASK, (x)))

static struct soc_device *soc_dev;
static struct soc_device_attribute *soc_dev_attr;

#ifdef CONFIG_ARM64

static char __ro_after_init smccc_soc_id_name[136] = "";

static inline void str_fragment_from_reg(char *dst, unsigned long reg)
{
        dst[0] = (reg >> 0)  & 0xff;
        dst[1] = (reg >> 8)  & 0xff;
        dst[2] = (reg >> 16) & 0xff;
        dst[3] = (reg >> 24) & 0xff;
        dst[4] = (reg >> 32) & 0xff;
        dst[5] = (reg >> 40) & 0xff;
        dst[6] = (reg >> 48) & 0xff;
        dst[7] = (reg >> 56) & 0xff;
}

static char __init *smccc_soc_name_init(void)
{
        struct arm_smccc_1_2_regs args;
        struct arm_smccc_1_2_regs res;
        size_t len;

        /*
         * Issue Number 1.6 of the Arm SMC Calling Convention
         * specification introduces an optional "name" string
         * to the ARM_SMCCC_ARCH_SOC_ID function.  Fetch it if
         * available.
         */
        args.a0 = ARM_SMCCC_ARCH_SOC_ID;
        args.a1 = 2;    /* SOC_ID name */
        arm_smccc_1_2_invoke(&args, &res);

        if ((u32)res.a0 == 0) {
                /*
                 * Copy res.a1..res.a17 to the smccc_soc_id_name string
                 * 8 bytes at a time.  As per Issue 1.6 of the Arm SMC
                 * Calling Convention, the string will be NUL terminated
                 * and padded, from the end of the string to the end of the
                 * 136 byte buffer, with NULs.
                 */
                str_fragment_from_reg(smccc_soc_id_name + 8 * 0, res.a1);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 1, res.a2);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 2, res.a3);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 3, res.a4);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 4, res.a5);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 5, res.a6);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 6, res.a7);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 7, res.a8);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 8, res.a9);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 9, res.a10);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 10, res.a11);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 11, res.a12);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 12, res.a13);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 13, res.a14);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 14, res.a15);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 15, res.a16);
                str_fragment_from_reg(smccc_soc_id_name + 8 * 16, res.a17);

                len = strnlen(smccc_soc_id_name, sizeof(smccc_soc_id_name));
                if (len) {
                        if (len == sizeof(smccc_soc_id_name))
                                pr_warn(FW_BUG "Ignoring improperly formatted name\n");
                        else
                                return smccc_soc_id_name;
                }
        }

        return NULL;
}

#else

static char __init *smccc_soc_name_init(void)
{
        return NULL;
}

#endif

static int __init smccc_soc_init(void)
{
        int soc_id_rev, soc_id_version;
        static char soc_id_str[20], soc_id_rev_str[12];
        static char soc_id_jep106_id_str[12];

        if (arm_smccc_get_version() < ARM_SMCCC_VERSION_1_2)
                return 0;

        soc_id_version = arm_smccc_get_soc_id_version();
        if (soc_id_version == SMCCC_RET_NOT_SUPPORTED) {
                pr_info("ARCH_SOC_ID not implemented, skipping ....\n");
                return 0;
        }

        if (soc_id_version < 0) {
                pr_err("Invalid SoC Version: %x\n", soc_id_version);
                return -EINVAL;
        }

        soc_id_rev = arm_smccc_get_soc_id_revision();
        if (soc_id_rev < 0) {
                pr_err("Invalid SoC Revision: %x\n", soc_id_rev);
                return -EINVAL;
        }

        soc_dev_attr = kzalloc_obj(*soc_dev_attr);
        if (!soc_dev_attr)
                return -ENOMEM;

        sprintf(soc_id_rev_str, "0x%08x", soc_id_rev);
        sprintf(soc_id_jep106_id_str, "jep106:%02x%02x",
                JEP106_BANK_CONT_CODE(soc_id_version),
                JEP106_ID_CODE(soc_id_version));
        sprintf(soc_id_str, "%s:%04x", soc_id_jep106_id_str,
                IMP_DEF_SOC_ID(soc_id_version));

        soc_dev_attr->soc_id = soc_id_str;
        soc_dev_attr->revision = soc_id_rev_str;
        soc_dev_attr->family = soc_id_jep106_id_str;
        soc_dev_attr->machine = smccc_soc_name_init();

        soc_dev = soc_device_register(soc_dev_attr);
        if (IS_ERR(soc_dev)) {
                kfree(soc_dev_attr);
                return PTR_ERR(soc_dev);
        }

        pr_info("ID = %s Revision = %s\n", soc_dev_attr->soc_id,
                soc_dev_attr->revision);

        return 0;
}
module_init(smccc_soc_init);

static void __exit smccc_soc_exit(void)
{
        if (soc_dev)
                soc_device_unregister(soc_dev);
        kfree(soc_dev_attr);
}
module_exit(smccc_soc_exit);