soc: Add Amlogic SoC Information driver

Amlogic SoCs have a SoC information register for SoC type, package type and
revision information.
This patchs adds support for this register decoding and exposing with the
SoC bus infrastructure.

Signed-off-by: Neil Armstrong <[e-mail]>
Signed-off-by: Kevin Hilman <[e-mail]>

drivers/soc/Kconfig

···
 menu "SOC (System On Chip) specific Drivers"
 
 source "drivers/soc/actions/Kconfig"
+source "drivers/soc/amlogic/Kconfig"
 source "drivers/soc/atmel/Kconfig"
 source "drivers/soc/bcm/Kconfig"
 source "drivers/soc/fsl/Kconfig"

drivers/soc/Makefile

···
 obj-y				+= fsl/
 obj-$(CONFIG_ARCH_MXC)		+= imx/
 obj-$(CONFIG_ARCH_MEDIATEK)	+= mediatek/
+obj-$(CONFIG_ARCH_MESON)	+= amlogic/
 obj-$(CONFIG_ARCH_QCOM)		+= qcom/
 obj-y				+= renesas/
 obj-$(CONFIG_ARCH_ROCKCHIP)	+= rockchip/

drivers/soc/amlogic/Kconfig

···
+menu "Amlogic SoC drivers"
+
+config MESON_GX_SOCINFO
+	bool "Amlogic Meson GX SoC Information driver"
+	depends on ARCH_MESON || COMPILE_TEST
+	default ARCH_MESON
+	select SOC_BUS
+	help
+	  Say yes to support decoding of Amlogic Meson GX SoC family
+	  information about the type, package and version.
+
+endmenu

drivers/soc/amlogic/Makefile

···
+obj-$(CONFIG_MESON_GX_SOCINFO) += meson-gx-socinfo.o

drivers/soc/amlogic/meson-gx-socinfo.c

···
+/*
+ * Copyright (c) 2017 BayLibre, SAS
+ * Author: Neil Armstrong <[e-mail]>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+#include <linux/bitfield.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+
+#define AO_SEC_SD_CFG8		0xe0
+#define AO_SEC_SOCINFO_OFFSET	AO_SEC_SD_CFG8
+
+#define SOCINFO_MAJOR	GENMASK(31, 24)
+#define SOCINFO_MINOR	GENMASK(23, 16)
+#define SOCINFO_PACK	GENMASK(15, 8)
+#define SOCINFO_MISC	GENMASK(7, 0)
+
+static const struct meson_gx_soc_id {
+	const char *name;
+	unsigned int id;
+} soc_ids[] = {
+	{ "GXBB", 0x1f },
+	{ "GXTVBB", 0x20 },
+	{ "GXL", 0x21 },
+	{ "GXM", 0x22 },
+	{ "TXL", 0x23 },
+};
+
+static const struct meson_gx_package_id {
+	const char *name;
+	unsigned int major_id;
+	unsigned int pack_id;
+} soc_packages[] = {
+	{ "S905", 0x1f, 0 },
+	{ "S905M", 0x1f, 0x20 },
+	{ "S905D", 0x21, 0 },
+	{ "S905X", 0x21, 0x80 },
+	{ "S905L", 0x21, 0xc0 },
+	{ "S905M2", 0x21, 0xe0 },
+	{ "S912", 0x22, 0 },
+};
+
+static inline unsigned int socinfo_to_major(u32 socinfo)
+{
+	return FIELD_GET(SOCINFO_MAJOR, socinfo);
+}
+
+static inline unsigned int socinfo_to_minor(u32 socinfo)
+{
+	return FIELD_GET(SOCINFO_MINOR, socinfo);
+}
+
+static inline unsigned int socinfo_to_pack(u32 socinfo)
+{
+	return FIELD_GET(SOCINFO_PACK, socinfo);
+}
+
+static inline unsigned int socinfo_to_misc(u32 socinfo)
+{
+	return FIELD_GET(SOCINFO_MISC, socinfo);
+}
+
+static const char *socinfo_to_package_id(u32 socinfo)
+{
+	unsigned int pack = socinfo_to_pack(socinfo) & 0xf0;
+	unsigned int major = socinfo_to_major(socinfo);
+	int i;
+
+	for (i = 0 ; i < ARRAY_SIZE(soc_packages) ; ++i) {
+		if (soc_packages[i].major_id == major &&
+		    soc_packages[i].pack_id == pack)
+			return soc_packages[i].name;
+	}
+
+	return "Unknown";
+}
+
+static const char *socinfo_to_soc_id(u32 socinfo)
+{
+	unsigned int id = socinfo_to_major(socinfo);
+	int i;
+
+	for (i = 0 ; i < ARRAY_SIZE(soc_ids) ; ++i) {
+		if (soc_ids[i].id == id)
+			return soc_ids[i].name;
+	}
+
+	return "Unknown";
+}
+
+int __init meson_gx_socinfo_init(void)
+{
+	struct soc_device_attribute *soc_dev_attr;
+	struct soc_device *soc_dev;
+	struct device_node *np;
+	struct regmap *regmap;
+	unsigned int socinfo;
+	struct device *dev;
+	int ret;
+
+	/* look up for chipid node */
+	np = of_find_compatible_node(NULL, NULL, "amlogic,meson-gx-ao-secure");
+	if (!np)
+		return -ENODEV;
+
+	/* check if interface is enabled */
+	if (!of_device_is_available(np))
+		return -ENODEV;
+
+	/* check if chip-id is available */
+	if (!of_property_read_bool(np, "amlogic,has-chip-id"))
+		return -ENODEV;
+
+	/* node should be a syscon */
+	regmap = syscon_node_to_regmap(np);
+	of_node_put(np);
+	if (IS_ERR(regmap)) {
+		pr_err("%s: failed to get regmap\n", __func__);
+		return -ENODEV;
+	}
+
+	ret = regmap_read(regmap, AO_SEC_SOCINFO_OFFSET, &socinfo);
+	if (ret < 0)
+		return ret;
+
+	if (!socinfo) {
+		pr_err("%s: invalid chipid value\n", __func__);
+		return -EINVAL;
+	}
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENODEV;
+
+	soc_dev_attr->family = "Amlogic Meson";
+
+	np = of_find_node_by_path("/");
+	of_property_read_string(np, "model", &soc_dev_attr->machine);
+	of_node_put(np);
+
+	soc_dev_attr->revision = kasprintf(GFP_KERNEL, "%x:%x - %x:%x",
+					   socinfo_to_major(socinfo),
+					   socinfo_to_minor(socinfo),
+					   socinfo_to_pack(socinfo),
+					   socinfo_to_misc(socinfo));
+	soc_dev_attr->soc_id = kasprintf(GFP_KERNEL, "%s (%s)",
+					 socinfo_to_soc_id(socinfo),
+					 socinfo_to_package_id(socinfo));
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr->revision);
+		kfree_const(soc_dev_attr->soc_id);
+		kfree(soc_dev_attr);
+		return PTR_ERR(soc_dev);
+	}
+	dev = soc_device_to_device(soc_dev);
+
+	dev_info(dev, "Amlogic Meson %s Revision %x:%x (%x:%x) Detected\n",
+			soc_dev_attr->soc_id,
+			socinfo_to_major(socinfo),
+			socinfo_to_minor(socinfo),
+			socinfo_to_pack(socinfo),
+			socinfo_to_misc(socinfo));
+
+	return 0;
+}
+device_initcall(meson_gx_socinfo_init);