[PATCH 5/5] arm/arm64: smccc: Add ARCH_SOC_ID support

[Sudeep Holla]

SMCCC v1.2 adds a new optional function SMCCC_ARCH_SOC_ID to obtain a
SiP defined SoC identification value. Add support for the same.

Also using the SoC bus infrastructure, let us expose the platform
specific SoC atrributes under sysfs. We also provide custom sysfs for
the vendor ID as JEP-106 bank and identification code.

Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
 drivers/firmware/psci/Makefile |   2 +-
 drivers/firmware/psci/soc_id.c | 148 +++++++++++++++++++++++++++++++++
 include/linux/arm-smccc.h      |   5 ++
 3 files changed, 154 insertions(+), 1 deletion(-)
 create mode 100644 drivers/firmware/psci/soc_id.c

diff --git a/drivers/firmware/psci/Makefile b/drivers/firmware/psci/Makefile
index 1956b882470f..c0b0c9ca57e4 100644
--- a/drivers/firmware/psci/Makefile
+++ b/drivers/firmware/psci/Makefile
@@ -1,4 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0
 #
-obj-$(CONFIG_ARM_PSCI_FW)	+= psci.o
+obj-$(CONFIG_ARM_PSCI_FW)	+= psci.o soc_id.o
 obj-$(CONFIG_ARM_PSCI_CHECKER)	+= psci_checker.o
diff --git a/drivers/firmware/psci/soc_id.c b/drivers/firmware/psci/soc_id.c
new file mode 100644
index 000000000000..820f69dad7f5
--- /dev/null
+++ b/drivers/firmware/psci/soc_id.c
@@ -0,0 +1,148 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Arm Limited
+ */
+
+#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 SOCID_JEP106_BANK_IDX_MASK	GENMASK(30, 24)
+#define SOCID_JEP106_ID_CODE_MASK	GENMASK(23, 16)
+#define SOCID_IMP_DEF_SOC_ID_MASK	GENMASK(15, 0)
+#define JEP106_BANK_IDX(x)	(u8)(FIELD_GET(SOCID_JEP106_BANK_IDX_MASK, (x)))
+#define JEP106_ID_CODE(x)	(u8)(FIELD_GET(SOCID_JEP106_ID_CODE_MASK, (x)))
+#define IMP_DEF_SOC_ID(x)	(u16)(FIELD_GET(SOCID_IMP_DEF_SOC_ID_MASK, (x)))
+
+static int soc_id_version;
+static struct soc_device *soc_dev;
+static struct soc_device_attribute *soc_dev_attr;
+
+static int smccc_map_error_codes(unsigned long a0)
+{
+	if (a0 == SMCCC_RET_INVALID_PARAMETER)
+		return -EINVAL;
+	if (a0 == SMCCC_RET_NOT_SUPPORTED)
+		return -EOPNOTSUPP;
+	return 0;
+}
+
+static int smccc_soc_id_support_check(void)
+{
+	struct arm_smccc_res res;
+
+	if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE) {
+		pr_err("%s: invalid SMCCC conduit\n", __func__);
+		return -EOPNOTSUPP;
+	}
+
+	arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
+			     ARM_SMCCC_ARCH_SOC_ID, &res);
+
+	return smccc_map_error_codes(res.a0);
+}
+
+static ssize_t
+jep106_cont_bank_code_show(struct device *dev, struct device_attribute *attr,
+			   char *buf)
+{
+	return sprintf(buf, "%02x\n", JEP106_BANK_IDX(soc_id_version) + 1);
+}
+
+static DEVICE_ATTR_RO(jep106_cont_bank_code);
+
+static ssize_t
+jep106_identification_code_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%02x\n", JEP106_ID_CODE(soc_id_version) & 0x7F);
+}
+
+static DEVICE_ATTR_RO(jep106_identification_code);
+
+static struct attribute *jep106_id_attrs[] = {
+	&dev_attr_jep106_cont_bank_code.attr,
+	&dev_attr_jep106_identification_code.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(jep106_id);
+
+static int __init smccc_soc_init(void)
+{
+	struct device *dev;
+	int ret, soc_id_rev;
+	struct arm_smccc_res res;
+	static char soc_id_str[8], soc_id_rev_str[12];
+
+	if (arm_smccc_get_version() < ARM_SMCCC_VERSION_1_2)
+		return 0;
+
+	ret = smccc_soc_id_support_check();
+	if (ret)
+		return ret;
+
+	arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_SOC_ID, 0, &res);
+
+	ret = smccc_map_error_codes(res.a0);
+	if (ret)
+		return ret;
+
+	soc_id_version = res.a0;
+
+	arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_SOC_ID, 1, &res);
+
+	ret = smccc_map_error_codes(res.a0);
+	if (ret)
+		return ret;
+
+	soc_id_rev = res.a0;
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	sprintf(soc_id_str, "0x%04x", IMP_DEF_SOC_ID(soc_id_version));
+	sprintf(soc_id_rev_str, "0x%08x", soc_id_rev);
+
+	soc_dev_attr->soc_id = soc_id_str;
+	soc_dev_attr->revision = soc_id_rev_str;
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		ret = PTR_ERR(soc_dev);
+		goto free_soc;
+	}
+
+	dev = soc_device_to_device(soc_dev);
+
+	ret = devm_device_add_groups(dev, jep106_id_groups);
+	if (ret) {
+		dev_err(dev, "sysfs create failed: %d\n", ret);
+		goto unregister_soc;
+	}
+
+	pr_info("SMCCC SoC ID: %s Revision %s\n", soc_dev_attr->soc_id,
+		soc_dev_attr->revision);
+
+	return 0;
+
+unregister_soc:
+	soc_device_unregister(soc_dev);
+free_soc:
+	kfree(soc_dev_attr);
+	return ret;
+}
+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);
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index d6b0f4acc707..04414fc2000f 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -68,6 +68,11 @@
 			   ARM_SMCCC_SMC_32,				\
 			   0, 1)
 
+#define ARM_SMCCC_ARCH_SOC_ID						\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
+			   ARM_SMCCC_SMC_32,				\
+			   0, 2)
+
 #define ARM_SMCCC_ARCH_WORKAROUND_1					\
 	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,				\
 			   ARM_SMCCC_SMC_32,				\
-- 
2.17.1