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>

1 files changed, 161 insertions, 0 deletions

diff --git a/arch/mips/ath25/board.c b/arch/mips/ath25/board.c
index d4675e04a634..b8bb78282d6a 100644
--- a/arch/mips/ath25/board.c
+++ b/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();