mips: ralink: mt7620: introduce 'soc_device' initialization

MT7620 SoCs have their own 'ralink_soc_info' structure with some
information about the soc itself. In order to be able to retrieve this
information from driver code and avoid architecture dependencies for
retrieving these details introduce this 'soc_device'. Set 'data' pointer
points to the struct 'ralink_soc_info' to be able to export also current
soc information using this mechanism. We need to select 'SOC_BUS' in
Kconfig configuration for these SoCs.
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/ralink/Kconfig

@@ -44,6 +44,7 @@ choice
 		bool "MT7620/8"
 		select CPU_MIPSR2_IRQ_VI
 		select HAVE_PCI
+		select SOC_BUS
 
 	config SOC_MT7621
 		bool "MT7621"

arch/mips/ralink/mt7620.c

@@ -11,6 +11,8 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/bug.h>
+#include <linux/slab.h>
+#include <linux/sys_soc.h>
 
 #include <asm/mipsregs.h>
 #include <asm/mach-ralink/ralink_regs.h>
@@ -49,6 +51,8 @@
 /* does the board have sdram or ddram */
 static int dram_type;
 
+static struct ralink_soc_info *soc_info_ptr;
+
 static __init u32
 mt7620_calc_rate(u32 ref_rate, u32 mul, u32 div)
 {
@@ -410,6 +414,44 @@ static const char __init *mt7620_get_soc_name(struct ralink_soc_info *soc_info)
 	}
 }
 
+static const char __init *mt7620_get_soc_id_name(void)
+{
+	if (ralink_soc == MT762X_SOC_MT7620A)
+		return "mt7620a";
+	else if (ralink_soc == MT762X_SOC_MT7620N)
+		return "mt7620n";
+	else if (ralink_soc == MT762X_SOC_MT7688)
+		return "mt7688";
+	else if (ralink_soc == MT762X_SOC_MT7628AN)
+		return "mt7628n";
+	else
+		return "invalid";
+}
+
+static int __init mt7620_soc_dev_init(void)
+{
+	struct soc_device *soc_dev;
+	struct soc_device_attribute *soc_dev_attr;
+
+	soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
+	if (!soc_dev_attr)
+		return -ENOMEM;
+
+	soc_dev_attr->family = "Ralink";
+	soc_dev_attr->soc_id = mt7620_get_soc_id_name();
+
+	soc_dev_attr->data = soc_info_ptr;
+
+	soc_dev = soc_device_register(soc_dev_attr);
+	if (IS_ERR(soc_dev)) {
+		kfree(soc_dev_attr);
+		return PTR_ERR(soc_dev);
+	}
+
+	return 0;
+}
+device_initcall(mt7620_soc_dev_init);
+
 void __init prom_soc_init(struct ralink_soc_info *soc_info)
 {
 	const char *name = mt7620_get_soc_name(soc_info);
@@ -444,4 +486,6 @@ void __init prom_soc_init(struct ralink_soc_info *soc_info)
 		(pmu0 & PMU_SW_SET) ? ("sw") : ("hw"));
 	pr_info("Digital PMU set to %s control\n",
 		(pmu1 & DIG_SW_SEL) ? ("sw") : ("hw"));
+
+	soc_info_ptr = soc_info;
 }