ARM: at91: add soc detection infrastructure

Add new structures and functions to handle AT91 SoC detection.

[alexandre.belloni@free-electrons.com: reworked DBGU detection]
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/Kconfig

@@ -363,6 +363,7 @@ config ARCH_AT91
 	select IRQ_DOMAIN
 	select PINCTRL
 	select PINCTRL_AT91
+	select SOC_BUS
 	select USE_OF
 	help
 	  This enables support for systems based on Atmel

arch/arm/mach-at91/Makefile

@@ -2,7 +2,7 @@
 # Makefile for the linux kernel.
 #
 
-obj-y		:= setup.o
+obj-y		:= setup.o soc.o
 
 obj-$(CONFIG_SOC_AT91SAM9)	+= sam9_smc.o
 

arch/arm/mach-at91/soc.c

@@ -0,0 +1,97 @@
+/*
+ * Copyright (C) 2015 Atmel
+ *
+ * Alexandre Belloni <alexandre.belloni@free-electrons.com
+ * Boris Brezillon <boris.brezillon@free-electrons.com
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ */
+
+#define pr_fmt(fmt)	"AT91: " fmt
+
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
+
+#include "soc.h"
+
+#define AT91_DBGU_CIDR			0x40
+#define AT91_DBGU_CIDR_VERSION(x)	((x) & 0x1f)
+#define AT91_DBGU_CIDR_EXT		BIT(31)
+#define AT91_DBGU_CIDR_MATCH_MASK	0x7fffffe0
+#define AT91_DBGU_EXID			0x44
+
+struct soc_device * __init at91_soc_init(const struct at91_soc *socs)
+{
+	struct soc_device_attribute *soc_dev_attr;
+	const struct at91_soc *soc;
+	struct soc_device *soc_dev;
+	struct device_node *np;
+	void __iomem *regs;
+	u32 cidr, exid;
+
+	np = of_find_compatible_node(NULL, NULL, "atmel,at91rm9200-dbgu");
+	if (!np)
+		np = of_find_compatible_node(NULL, NULL,
+					     "atmel,at91sam9260-dbgu");
+
+	if (!np) {
+		pr_warn("Could not find DBGU node");
+		return NULL;
+	}
+
+	regs = of_iomap(np, 0);
+	of_node_put(np);
+
+	if (!regs) {
+		pr_warn("Could not map DBGU iomem range");
+		return NULL;
+	}
+
+	cidr = readl(regs + AT91_DBGU_CIDR);
+	exid = readl(regs + AT91_DBGU_EXID);
+
+	iounmap(regs);
+
+	for (soc = socs; soc->name; soc++) {
+		if (soc->cidr_match != (cidr & AT91_DBGU_CIDR_MATCH_MASK))
+			continue;
+
+		if (!(cidr & AT91_DBGU_CIDR_EXT) || soc->exid_match == exid)
+			break;
+	}
+
+	if (!soc->name) {
+		pr_warn("Could not find matching SoC description\n");
+		return NULL;
+	}
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return NULL;
+
+	soc_dev_attr->family = soc->family;
+	soc_dev_attr->soc_id = soc->name;
+	soc_dev_attr->revision = kasprintf(GFP_KERNEL, "%X",
+					   AT91_DBGU_CIDR_VERSION(cidr));
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr->revision);
+		kfree(soc_dev_attr);
+		pr_warn("Could not register SoC device\n");
+		return NULL;
+	}
+
+	if (soc->family)
+		pr_info("Detected SoC family: %s\n", soc->family);
+	pr_info("Detected SoC: %s, revision %X\n", soc->name,
+		AT91_DBGU_CIDR_VERSION(cidr));
+
+	return soc_dev;
+}

arch/arm/mach-at91/soc.h

@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2015 Atmel
+ *
+ * Boris Brezillon <boris.brezillon@free-electrons.com
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ */
+
+#ifndef __AT91_SOC_H
+#define __AT91_SOC_H
+
+#include <linux/sys_soc.h>
+
+struct at91_soc {
+	u32 cidr_match;
+	u32 exid_match;
+	const char *name;
+	const char *family;
+};
+
+#define AT91_SOC(__cidr, __exid, __name, __family)		\
+	{							\
+		.cidr_match = (__cidr),				\
+		.exid_match = (__exid),				\
+		.name = (__name),				\
+		.family = (__family),				\
+	}
+
+struct soc_device * __init
+at91_soc_init(const struct at91_soc *socs);
+
+#endif /* __AT91_SOC_H */