soc_id.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright 2020 Arm Limited
  4 */
  5
  6#define pr_fmt(fmt) "SMCCC: SOC_ID: " fmt
  7
  8#include <linux/arm-smccc.h>
  9#include <linux/bitfield.h>
 10#include <linux/device.h>
 11#include <linux/module.h>
 12#include <linux/kernel.h>
 13#include <linux/slab.h>
 14#include <linux/sys_soc.h>
 15
 16#define SMCCC_SOC_ID_JEP106_BANK_IDX_MASK	GENMASK(30, 24)
 17/*
 18 * As per the SMC Calling Convention specification v1.2 (ARM DEN 0028C)
 19 * Section 7.4 SMCCC_ARCH_SOC_ID bits[23:16] are JEP-106 identification
 20 * code with parity bit for the SiP. We can drop the parity bit.
 21 */
 22#define SMCCC_SOC_ID_JEP106_ID_CODE_MASK	GENMASK(22, 16)
 23#define SMCCC_SOC_ID_IMP_DEF_SOC_ID_MASK	GENMASK(15, 0)
 24
 25#define JEP106_BANK_CONT_CODE(x)	\
 26	(u8)(FIELD_GET(SMCCC_SOC_ID_JEP106_BANK_IDX_MASK, (x)))
 27#define JEP106_ID_CODE(x)	\
 28	(u8)(FIELD_GET(SMCCC_SOC_ID_JEP106_ID_CODE_MASK, (x)))
 29#define IMP_DEF_SOC_ID(x)	\
 30	(u16)(FIELD_GET(SMCCC_SOC_ID_IMP_DEF_SOC_ID_MASK, (x)))
 31
 32static struct soc_device *soc_dev;
 33static struct soc_device_attribute *soc_dev_attr;
 34
 35#ifdef CONFIG_ARM64
 36
 37static char __ro_after_init smccc_soc_id_name[136] = "";
 38
 39static inline void str_fragment_from_reg(char *dst, unsigned long reg)
 40{
 41	dst[0] = (reg >> 0)  & 0xff;
 42	dst[1] = (reg >> 8)  & 0xff;
 43	dst[2] = (reg >> 16) & 0xff;
 44	dst[3] = (reg >> 24) & 0xff;
 45	dst[4] = (reg >> 32) & 0xff;
 46	dst[5] = (reg >> 40) & 0xff;
 47	dst[6] = (reg >> 48) & 0xff;
 48	dst[7] = (reg >> 56) & 0xff;
 49}
 50
 51static char __init *smccc_soc_name_init(void)
 52{
 53	struct arm_smccc_1_2_regs args;
 54	struct arm_smccc_1_2_regs res;
 55	size_t len;
 56
 57	/*
 58	 * Issue Number 1.6 of the Arm SMC Calling Convention
 59	 * specification introduces an optional "name" string
 60	 * to the ARM_SMCCC_ARCH_SOC_ID function.  Fetch it if
 61	 * available.
 62	 */
 63	args.a0 = ARM_SMCCC_ARCH_SOC_ID;
 64	args.a1 = 2;    /* SOC_ID name */
 65	arm_smccc_1_2_invoke(&args, &res);
 66
 67	if ((u32)res.a0 == 0) {
 68		/*
 69		 * Copy res.a1..res.a17 to the smccc_soc_id_name string
 70		 * 8 bytes at a time.  As per Issue 1.6 of the Arm SMC
 71		 * Calling Convention, the string will be NUL terminated
 72		 * and padded, from the end of the string to the end of the
 73		 * 136 byte buffer, with NULs.
 74		 */
 75		str_fragment_from_reg(smccc_soc_id_name + 8 * 0, res.a1);
 76		str_fragment_from_reg(smccc_soc_id_name + 8 * 1, res.a2);
 77		str_fragment_from_reg(smccc_soc_id_name + 8 * 2, res.a3);
 78		str_fragment_from_reg(smccc_soc_id_name + 8 * 3, res.a4);
 79		str_fragment_from_reg(smccc_soc_id_name + 8 * 4, res.a5);
 80		str_fragment_from_reg(smccc_soc_id_name + 8 * 5, res.a6);
 81		str_fragment_from_reg(smccc_soc_id_name + 8 * 6, res.a7);
 82		str_fragment_from_reg(smccc_soc_id_name + 8 * 7, res.a8);
 83		str_fragment_from_reg(smccc_soc_id_name + 8 * 8, res.a9);
 84		str_fragment_from_reg(smccc_soc_id_name + 8 * 9, res.a10);
 85		str_fragment_from_reg(smccc_soc_id_name + 8 * 10, res.a11);
 86		str_fragment_from_reg(smccc_soc_id_name + 8 * 11, res.a12);
 87		str_fragment_from_reg(smccc_soc_id_name + 8 * 12, res.a13);
 88		str_fragment_from_reg(smccc_soc_id_name + 8 * 13, res.a14);
 89		str_fragment_from_reg(smccc_soc_id_name + 8 * 14, res.a15);
 90		str_fragment_from_reg(smccc_soc_id_name + 8 * 15, res.a16);
 91		str_fragment_from_reg(smccc_soc_id_name + 8 * 16, res.a17);
 92
 93		len = strnlen(smccc_soc_id_name, sizeof(smccc_soc_id_name));
 94		if (len) {
 95			if (len == sizeof(smccc_soc_id_name))
 96				pr_warn(FW_BUG "Ignoring improperly formatted name\n");
 97			else
 98				return smccc_soc_id_name;
 99		}
100	}
101
102	return NULL;
103}
104
105#else
106
107static char __init *smccc_soc_name_init(void)
108{
109	return NULL;
110}
111
112#endif
113
114static int __init smccc_soc_init(void)
115{
116	int soc_id_rev, soc_id_version;
117	static char soc_id_str[20], soc_id_rev_str[12];
118	static char soc_id_jep106_id_str[12];
119
120	if (arm_smccc_get_version() < ARM_SMCCC_VERSION_1_2)
121		return 0;
122
123	soc_id_version = arm_smccc_get_soc_id_version();
124	if (soc_id_version == SMCCC_RET_NOT_SUPPORTED) {
125		pr_info("ARCH_SOC_ID not implemented, skipping ....\n");
126		return 0;
127	}
128
129	if (soc_id_version < 0) {
130		pr_err("Invalid SoC Version: %x\n", soc_id_version);
131		return -EINVAL;
132	}
133
134	soc_id_rev = arm_smccc_get_soc_id_revision();
135	if (soc_id_rev < 0) {
136		pr_err("Invalid SoC Revision: %x\n", soc_id_rev);
137		return -EINVAL;
138	}
139
140	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
141	if (!soc_dev_attr)
142		return -ENOMEM;
143
144	sprintf(soc_id_rev_str, "0x%08x", soc_id_rev);
145	sprintf(soc_id_jep106_id_str, "jep106:%02x%02x",
146		JEP106_BANK_CONT_CODE(soc_id_version),
147		JEP106_ID_CODE(soc_id_version));
148	sprintf(soc_id_str, "%s:%04x", soc_id_jep106_id_str,
149		IMP_DEF_SOC_ID(soc_id_version));
150
151	soc_dev_attr->soc_id = soc_id_str;
152	soc_dev_attr->revision = soc_id_rev_str;
153	soc_dev_attr->family = soc_id_jep106_id_str;
154	soc_dev_attr->machine = smccc_soc_name_init();
155
156	soc_dev = soc_device_register(soc_dev_attr);
157	if (IS_ERR(soc_dev)) {
158		kfree(soc_dev_attr);
159		return PTR_ERR(soc_dev);
160	}
161
162	pr_info("ID = %s Revision = %s\n", soc_dev_attr->soc_id,
163		soc_dev_attr->revision);
164
165	return 0;
166}
167module_init(smccc_soc_init);
168
169static void __exit smccc_soc_exit(void)
170{
171	if (soc_dev)
172		soc_device_unregister(soc_dev);
173	kfree(soc_dev_attr);
174}
175module_exit(smccc_soc_exit);