soc: ti: add k3 platforms chipid module driver

The Texas Instruments K3 Multicore SoC platforms have chipid module which
is represented by CTRLMMR_xxx_JTAGID register and contains information
about SoC id and revision.
 Bits:
  31-28 VARIANT Device variant
  27-12 PARTNO  Part number
  11-1  MFG     Indicates TI as manufacturer (0x17)
  1             Always 1

This patch adds corresponding driver to identify the TI K3 SoC family and
revision, and registers this information with the SoC bus. It is available
under /sys/devices/soc0/ for user space, and can be checked, where needed,
in Kernel using soc_device_match().

Identification is done by:
- checking MFG to be TI ID
 - retrieving Device variant (revision)
 - retrieving Part number and convert it to the family
 - retrieving machine from DT "/model"

Example J721E:
  # cat /sys/devices/soc0/{machine,family,revision}
  Texas Instruments K3 J721E SoC
  J721E
  SR1.0

Example AM65x:
  # cat /sys/devices/soc0/{machine,family,revision}
  Texas Instruments AM654 Base Board
  AM65X
  SR1.0

Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Reviewed-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

drivers/soc/ti/Kconfig

@@ -91,6 +91,16 @@ config TI_K3_RINGACC
 	  and a consumer. There is one RINGACC module per NAVSS on TI AM65x SoCs
 	  If unsure, say N.
 
+config TI_K3_SOCINFO
+	bool
+	depends on ARCH_K3 || COMPILE_TEST
+	select SOC_BUS
+	select MFD_SYSCON
+	help
+	  Include support for the SoC bus socinfo for the TI K3 Multicore SoC
+	  platforms to provide information about the SoC family and
+	  variant to user space.
+
 endif # SOC_TI
 
 config TI_SCI_INTA_MSI_DOMAIN

drivers/soc/ti/Makefile

@@ -11,3 +11,4 @@ obj-$(CONFIG_WKUP_M3_IPC)		+= wkup_m3_ipc.o
 obj-$(CONFIG_TI_SCI_PM_DOMAINS)		+= ti_sci_pm_domains.o
 obj-$(CONFIG_TI_SCI_INTA_MSI_DOMAIN)	+= ti_sci_inta_msi.o
 obj-$(CONFIG_TI_K3_RINGACC)		+= k3-ringacc.o
+obj-$(CONFIG_TI_K3_SOCINFO)		+= k3-socinfo.o

drivers/soc/ti/k3-socinfo.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * TI K3 SoC info driver
+ *
+ * Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com
+ */
+
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/sys_soc.h>
+
+#define CTRLMMR_WKUP_JTAGID_REG		0
+/*
+ * Bits:
+ *  31-28 VARIANT	Device variant
+ *  27-12 PARTNO	Part number
+ *  11-1  MFG		Indicates TI as manufacturer (0x17)
+ *  1			Always 1
+ */
+#define CTRLMMR_WKUP_JTAGID_VARIANT_SHIFT	(28)
+#define CTRLMMR_WKUP_JTAGID_VARIANT_MASK	GENMASK(31, 28)
+
+#define CTRLMMR_WKUP_JTAGID_PARTNO_SHIFT	(12)
+#define CTRLMMR_WKUP_JTAGID_PARTNO_MASK		GENMASK(27, 12)
+
+#define CTRLMMR_WKUP_JTAGID_MFG_SHIFT		(1)
+#define CTRLMMR_WKUP_JTAGID_MFG_MASK		GENMASK(11, 1)
+
+#define CTRLMMR_WKUP_JTAGID_MFG_TI		0x17
+
+static const struct k3_soc_id {
+	unsigned int id;
+	const char *family_name;
+} k3_soc_ids[] = {
+	{ 0xBB5A, "AM65X" },
+	{ 0xBB64, "J721E" },
+};
+
+static int
+k3_chipinfo_partno_to_names(unsigned int partno,
+			    struct soc_device_attribute *soc_dev_attr)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(k3_soc_ids); i++)
+		if (partno == k3_soc_ids[i].id) {
+			soc_dev_attr->family = k3_soc_ids[i].family_name;
+			return 0;
+		}
+
+	return -EINVAL;
+}
+
+static int k3_chipinfo_probe(struct platform_device *pdev)
+{
+	struct device_node *node = pdev->dev.of_node;
+	struct soc_device_attribute *soc_dev_attr;
+	struct device *dev = &pdev->dev;
+	struct soc_device *soc_dev;
+	struct regmap *regmap;
+	u32 partno_id;
+	u32 variant;
+	u32 jtag_id;
+	u32 mfg;
+	int ret;
+
+	regmap = device_node_to_regmap(node);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ret = regmap_read(regmap, CTRLMMR_WKUP_JTAGID_REG, &jtag_id);
+	if (ret < 0)
+		return ret;
+
+	mfg = (jtag_id & CTRLMMR_WKUP_JTAGID_MFG_MASK) >>
+	       CTRLMMR_WKUP_JTAGID_MFG_SHIFT;
+
+	if (mfg != CTRLMMR_WKUP_JTAGID_MFG_TI) {
+		dev_err(dev, "Invalid MFG SoC\n");
+		return -ENODEV;
+	}
+
+	variant = (jtag_id & CTRLMMR_WKUP_JTAGID_VARIANT_MASK) >>
+		  CTRLMMR_WKUP_JTAGID_VARIANT_SHIFT;
+	variant++;
+
+	partno_id = (jtag_id & CTRLMMR_WKUP_JTAGID_PARTNO_MASK) >>
+		 CTRLMMR_WKUP_JTAGID_PARTNO_SHIFT;
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	soc_dev_attr->revision = kasprintf(GFP_KERNEL, "SR%x.0", variant);
+	if (!soc_dev_attr->revision) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	ret = k3_chipinfo_partno_to_names(partno_id, soc_dev_attr);
+	if (ret) {
+		dev_err(dev, "Unknown SoC JTAGID[0x%08X]\n", jtag_id);
+		ret = -ENODEV;
+		goto err_free_rev;
+	}
+
+	node = of_find_node_by_path("/");
+	of_property_read_string(node, "model", &soc_dev_attr->machine);
+	of_node_put(node);
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		ret = PTR_ERR(soc_dev);
+		goto err_free_rev;
+	}
+
+	dev_info(dev, "Family:%s rev:%s JTAGID[0x%08x] Detected\n",
+		 soc_dev_attr->family,
+		 soc_dev_attr->revision, jtag_id);
+
+	return 0;
+
+err_free_rev:
+	kfree(soc_dev_attr->revision);
+err:
+	kfree(soc_dev_attr);
+	return ret;
+}
+
+static const struct of_device_id k3_chipinfo_of_match[] = {
+	{ .compatible = "ti,am654-chipid", },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver k3_chipinfo_driver = {
+	.driver = {
+		.name = "k3-chipinfo",
+		.of_match_table = k3_chipinfo_of_match,
+	},
+	.probe = k3_chipinfo_probe,
+};
+
+static int __init k3_chipinfo_init(void)
+{
+	return platform_driver_register(&k3_chipinfo_driver);
+}
+subsys_initcall(k3_chipinfo_init);