MIPS: ath25: add board configuration detection

All boards based on AR5312/AR2315 SoC have a special structure located
at the end of flash. This structure contains board-specific data such as
Ethernet and Wireless MAC addresses. The flash is mapped to the memmory
at predefined location.

Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Cc: Linux MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/8243/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/ath25/ar2315.c

@@ -160,6 +160,12 @@ void __init ar2315_arch_init_irq(void)
 	ar2315_misc_irq_domain = domain;
 }
 
+void __init ar2315_init_devices(void)
+{
+	/* Find board configuration */
+	ath25_find_config(AR2315_SPI_READ_BASE, AR2315_SPI_READ_SIZE);
+}
+
 static void ar2315_restart(char *command)
 {
 	void (*mips_reset_vec)(void) = (void *)0xbfc00000;

arch/mips/ath25/ar2315.h

@@ -4,6 +4,7 @@
 #ifdef CONFIG_SOC_AR2315
 
 void ar2315_arch_init_irq(void);
+void ar2315_init_devices(void);
 void ar2315_plat_time_init(void);
 void ar2315_plat_mem_setup(void);
 void ar2315_arch_init(void);
@@ -11,6 +12,7 @@ void ar2315_arch_init(void);
 #else
 
 static inline void ar2315_arch_init_irq(void) {}
+static inline void ar2315_init_devices(void) {}
 static inline void ar2315_plat_time_init(void) {}
 static inline void ar2315_plat_mem_setup(void) {}
 static inline void ar2315_arch_init(void) {}

arch/mips/ath25/ar5312.c

@@ -158,6 +158,45 @@ void __init ar5312_arch_init_irq(void)
 	ar5312_misc_irq_domain = domain;
 }
 
+static void __init ar5312_flash_init(void)
+{
+	void __iomem *flashctl_base;
+	u32 ctl;
+
+	flashctl_base = ioremap_nocache(AR5312_FLASHCTL_BASE,
+					AR5312_FLASHCTL_SIZE);
+
+	/*
+	 * Configure flash bank 0.
+	 * Assume 8M window size. Flash will be aliased if it's smaller
+	 */
+	ctl = __raw_readl(flashctl_base + AR5312_FLASHCTL0);
+	ctl &= AR5312_FLASHCTL_MW;
+	ctl |= AR5312_FLASHCTL_E | AR5312_FLASHCTL_AC_8M | AR5312_FLASHCTL_RBLE;
+	ctl |= 0x01 << AR5312_FLASHCTL_IDCY_S;
+	ctl |= 0x07 << AR5312_FLASHCTL_WST1_S;
+	ctl |= 0x07 << AR5312_FLASHCTL_WST2_S;
+	__raw_writel(ctl, flashctl_base + AR5312_FLASHCTL0);
+
+	/* Disable other flash banks */
+	ctl = __raw_readl(flashctl_base + AR5312_FLASHCTL1);
+	ctl &= ~(AR5312_FLASHCTL_E | AR5312_FLASHCTL_AC);
+	__raw_writel(ctl, flashctl_base + AR5312_FLASHCTL1);
+	ctl = __raw_readl(flashctl_base + AR5312_FLASHCTL2);
+	ctl &= ~(AR5312_FLASHCTL_E | AR5312_FLASHCTL_AC);
+	__raw_writel(ctl, flashctl_base + AR5312_FLASHCTL2);
+
+	iounmap(flashctl_base);
+}
+
+void __init ar5312_init_devices(void)
+{
+	ar5312_flash_init();
+
+	/* Locate board/radio config data */
+	ath25_find_config(AR5312_FLASH_BASE, AR5312_FLASH_SIZE);
+}
+
 static void ar5312_restart(char *command)
 {
 	/* reset the system */

arch/mips/ath25/ar5312.h

@@ -4,6 +4,7 @@
 #ifdef CONFIG_SOC_AR5312
 
 void ar5312_arch_init_irq(void);
+void ar5312_init_devices(void);
 void ar5312_plat_time_init(void);
 void ar5312_plat_mem_setup(void);
 void ar5312_arch_init(void);
@@ -11,6 +12,7 @@ void ar5312_arch_init(void);
 #else
 
 static inline void ar5312_arch_init_irq(void) {}
+static inline void ar5312_init_devices(void) {}
 static inline void ar5312_plat_time_init(void) {}
 static inline void ar5312_plat_mem_setup(void) {}
 static inline void ar5312_arch_init(void) {}

arch/mips/ath25/board.c

@@ -16,12 +16,173 @@
 #include <asm/bootinfo.h>
 #include <asm/time.h>
 
+#include <ath25_platform.h>
 #include "devices.h"
 #include "ar5312.h"
 #include "ar2315.h"
 
 void (*ath25_irq_dispatch)(void);
 
+static inline bool check_radio_magic(const void __iomem *addr)
+{
+	addr += 0x7a; /* offset for flash magic */
+	return (__raw_readb(addr) == 0x5a) && (__raw_readb(addr + 1) == 0xa5);
+}
+
+static inline bool check_notempty(const void __iomem *addr)
+{
+	return __raw_readl(addr) != 0xffffffff;
+}
+
+static inline bool check_board_data(const void __iomem *addr, bool broken)
+{
+	/* config magic found */
+	if (__raw_readl(addr) == ATH25_BD_MAGIC)
+		return true;
+
+	if (!broken)
+		return false;
+
+	/* broken board data detected, use radio data to find the
+	 * offset, user will fix this */
+
+	if (check_radio_magic(addr + 0x1000))
+		return true;
+	if (check_radio_magic(addr + 0xf8))
+		return true;
+
+	return false;
+}
+
+static const void __iomem * __init find_board_config(const void __iomem *limit,
+						     const bool broken)
+{
+	const void __iomem *addr;
+	const void __iomem *begin = limit - 0x1000;
+	const void __iomem *end = limit - 0x30000;
+
+	for (addr = begin; addr >= end; addr -= 0x1000)
+		if (check_board_data(addr, broken))
+			return addr;
+
+	return NULL;
+}
+
+static const void __iomem * __init find_radio_config(const void __iomem *limit,
+						     const void __iomem *bcfg)
+{
+	const void __iomem *rcfg, *begin, *end;
+
+	/*
+	 * Now find the start of Radio Configuration data, using heuristics:
+	 * Search forward from Board Configuration data by 0x1000 bytes
+	 * at a time until we find non-0xffffffff.
+	 */
+	begin = bcfg + 0x1000;
+	end = limit;
+	for (rcfg = begin; rcfg < end; rcfg += 0x1000)
+		if (check_notempty(rcfg) && check_radio_magic(rcfg))
+			return rcfg;
+
+	/* AR2316 relocates radio config to new location */
+	begin = bcfg + 0xf8;
+	end = limit - 0x1000 + 0xf8;
+	for (rcfg = begin; rcfg < end; rcfg += 0x1000)
+		if (check_notempty(rcfg) && check_radio_magic(rcfg))
+			return rcfg;
+
+	return NULL;
+}
+
+/*
+ * NB: Search region size could be larger than the actual flash size,
+ * but this shouldn't be a problem here, because the flash
+ * will simply be mapped multiple times.
+ */
+int __init ath25_find_config(phys_addr_t base, unsigned long size)
+{
+	const void __iomem *flash_base, *flash_limit;
+	struct ath25_boarddata *config;
+	unsigned int rcfg_size;
+	int broken_boarddata = 0;
+	const void __iomem *bcfg, *rcfg;
+	u8 *board_data;
+	u8 *radio_data;
+	u8 *mac_addr;
+	u32 offset;
+
+	flash_base = ioremap_nocache(base, size);
+	flash_limit = flash_base + size;
+
+	ath25_board.config = NULL;
+	ath25_board.radio = NULL;
+
+	/* Copy the board and radio data to RAM, because accessing the mapped
+	 * memory of the flash directly after booting is not safe */
+
+	/* Try to find valid board and radio data */
+	bcfg = find_board_config(flash_limit, false);
+
+	/* If that fails, try to at least find valid radio data */
+	if (!bcfg) {
+		bcfg = find_board_config(flash_limit, true);
+		broken_boarddata = 1;
+	}
+
+	if (!bcfg) {
+		pr_warn("WARNING: No board configuration data found!\n");
+		goto error;
+	}
+
+	board_data = kzalloc(BOARD_CONFIG_BUFSZ, GFP_KERNEL);
+	ath25_board.config = (struct ath25_boarddata *)board_data;
+	memcpy_fromio(board_data, bcfg, 0x100);
+	if (broken_boarddata) {
+		pr_warn("WARNING: broken board data detected\n");
+		config = ath25_board.config;
+		if (is_zero_ether_addr(config->enet0_mac)) {
+			pr_info("Fixing up empty mac addresses\n");
+			config->reset_config_gpio = 0xffff;
+			config->sys_led_gpio = 0xffff;
+			random_ether_addr(config->wlan0_mac);
+			config->wlan0_mac[0] &= ~0x06;
+			random_ether_addr(config->enet0_mac);
+			random_ether_addr(config->enet1_mac);
+		}
+	}
+
+	/* Radio config starts 0x100 bytes after board config, regardless
+	 * of what the physical layout on the flash chip looks like */
+
+	rcfg = find_radio_config(flash_limit, bcfg);
+	if (!rcfg) {
+		pr_warn("WARNING: Could not find Radio Configuration data\n");
+		goto error;
+	}
+
+	radio_data = board_data + 0x100 + ((rcfg - bcfg) & 0xfff);
+	ath25_board.radio = radio_data;
+	offset = radio_data - board_data;
+	pr_info("Radio config found at offset 0x%x (0x%x)\n", rcfg - bcfg,
+		offset);
+	rcfg_size = BOARD_CONFIG_BUFSZ - offset;
+	memcpy_fromio(radio_data, rcfg, rcfg_size);
+
+	mac_addr = &radio_data[0x1d * 2];
+	if (is_broadcast_ether_addr(mac_addr)) {
+		pr_info("Radio MAC is blank; using board-data\n");
+		ether_addr_copy(mac_addr, ath25_board.config->wlan0_mac);
+	}
+
+	iounmap(flash_base);
+
+	return 0;
+
+error:
+	iounmap(flash_base);
+	return -ENODEV;
+}
+
 static void ath25_halt(void)
 {
 	local_irq_disable();

arch/mips/ath25/devices.c

@@ -3,10 +3,13 @@
 #include <linux/serial_8250.h>
 #include <asm/bootinfo.h>
 
+#include <ath25_platform.h>
 #include "devices.h"
 #include "ar5312.h"
 #include "ar2315.h"
 
+struct ar231x_board_config ath25_board;
+
 const char *get_system_type(void)
 {
 	return "Atheros (unknown)";
@@ -28,6 +31,18 @@ void __init ath25_serial_setup(u32 mapbase, int irq, unsigned int uartclk)
 	early_serial_setup(&s);
 }
 
+static int __init ath25_register_devices(void)
+{
+	if (is_ar5312())
+		ar5312_init_devices();
+	else
+		ar2315_init_devices();
+
+	return 0;
+}
+
+device_initcall(ath25_register_devices);
+
 static int __init ath25_arch_init(void)
 {
 	if (is_ar5312())

arch/mips/ath25/devices.h

@@ -7,8 +7,10 @@
 
 #define ATH25_IRQ_CPU_CLOCK	(MIPS_CPU_IRQ_BASE + 7)	/* C0_CAUSE: 0x8000 */
 
+extern struct ar231x_board_config ath25_board;
 extern void (*ath25_irq_dispatch)(void);
 
+int ath25_find_config(phys_addr_t offset, unsigned long size);
 void ath25_serial_setup(u32 mapbase, int irq, unsigned int uartclk);
 
 static inline bool is_ar2315(void)