am33xx: add ELM support

AM33XX has Error Location Module (ELM) that can be used in conjuction
with GPMC controller to implement BCH codes fully in hardware.
This code is mostly taken from arago tree.

Signed-off-by: Mansoor Ahamed <mansoor.ahamed@ti.com>
Signed-off-by: Ilya Yanok <ilya.yanok@cogentembedded.com>

arch/arm/cpu/armv7/am33xx/Makefile

@@ -23,6 +23,7 @@ COBJS	+= ddr.o
 COBJS	+= emif4.o
 COBJS	+= board.o
 COBJS	+= mux.o
+COBJS-$(CONFIG_NAND_OMAP_GPMC)	+= elm.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS:.o=.c)
 OBJS	:= $(addprefix $(obj),$(COBJS) $(COBJS-y) $(SOBJS))

arch/arm/cpu/armv7/am33xx/clock.c

@@ -155,6 +155,11 @@ static void enable_per_clocks(void)
 	while (readl(&cmper->gpmcclkctrl) != PRCM_MOD_EN)
 		;
 
+	/* ELM */
+	writel(PRCM_MOD_EN, &cmper->elmclkctrl);
+	while (readl(&cmper->elmclkctrl) != PRCM_MOD_EN)
+		;
+
 	/* MMC0*/
 	writel(PRCM_MOD_EN, &cmper->mmc0clkctrl);
 	while (readl(&cmper->mmc0clkctrl) != PRCM_MOD_EN)

arch/arm/cpu/armv7/am33xx/elm.c

@@ -0,0 +1,212 @@
+/*
+ * (C) Copyright 2010-2011 Texas Instruments, <www.ti.com>
+ * Mansoor Ahamed <mansoor.ahamed@ti.com>
+ *
+ * BCH Error Location Module (ELM) support.
+ *
+ * NOTE:
+ * 1. Supports only continuous mode. Dont see need for page mode in uboot
+ * 2. Supports only syndrome polynomial 0. i.e. poly local variable is
+ *    always set to ELM_DEFAULT_POLY. Dont see need for other polynomial
+ *    sets in uboot
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/errno.h>
+#include <asm/arch/cpu.h>
+#include <asm/arch/omap_gpmc.h>
+#include <asm/arch/elm.h>
+
+#define ELM_DEFAULT_POLY (0)
+
+struct elm *elm_cfg;
+
+/**
+ * elm_load_syndromes - Load BCH syndromes based on nibble selection
+ * @syndrome: BCH syndrome
+ * @nibbles:
+ * @poly: Syndrome Polynomial set to use
+ *
+ * Load BCH syndromes based on nibble selection
+ */
+static void elm_load_syndromes(u8 *syndrome, u32 nibbles, u8 poly)
+{
+	u32 *ptr;
+	u32 val;
+
+	/* reg 0 */
+	ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[0];
+	val = syndrome[0] | (syndrome[1] << 8) | (syndrome[2] << 16) |
+				(syndrome[3] << 24);
+	writel(val, ptr);
+	/* reg 1 */
+	ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[1];
+	val = syndrome[4] | (syndrome[5] << 8) | (syndrome[6] << 16) |
+				(syndrome[7] << 24);
+	writel(val, ptr);
+
+	/* BCH 8-bit with 26 nibbles (4*8=32) */
+	if (nibbles > 13) {
+		/* reg 2 */
+		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[2];
+		val = syndrome[8] | (syndrome[9] << 8) | (syndrome[10] << 16) |
+				(syndrome[11] << 24);
+		writel(val, ptr);
+		/* reg 3 */
+		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[3];
+		val = syndrome[12] | (syndrome[13] << 8) |
+			(syndrome[14] << 16) | (syndrome[15] << 24);
+		writel(val, ptr);
+	}
+
+	/* BCH 16-bit with 52 nibbles (7*8=56) */
+	if (nibbles > 26) {
+		/* reg 4 */
+		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[4];
+		val = syndrome[16] | (syndrome[17] << 8) |
+			(syndrome[18] << 16) | (syndrome[19] << 24);
+		writel(val, ptr);
+
+		/* reg 5 */
+		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[5];
+		val = syndrome[20] | (syndrome[21] << 8) |
+			(syndrome[22] << 16) | (syndrome[23] << 24);
+		writel(val, ptr);
+
+		/* reg 6 */
+		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6];
+		val = syndrome[24] | (syndrome[25] << 8) |
+			(syndrome[26] << 16) | (syndrome[27] << 24);
+		writel(val, ptr);
+	}
+}
+
+/**
+ * elm_check_errors - Check for BCH errors and return error locations
+ * @syndrome: BCH syndrome
+ * @nibbles:
+ * @error_count: Returns number of errrors in the syndrome
+ * @error_locations: Returns error locations (in decimal) in this array
+ *
+ * Check the provided syndrome for BCH errors and return error count
+ * and locations in the array passed. Returns -1 if error is not correctable,
+ * else returns 0
+ */
+int elm_check_error(u8 *syndrome, u32 nibbles, u32 *error_count,
+		u32 *error_locations)
+{
+	u8 poly = ELM_DEFAULT_POLY;
+	s8 i;
+	u32 location_status;
+
+	elm_load_syndromes(syndrome, nibbles, poly);
+
+	/* start processing */
+	writel((readl(&elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6])
+				| ELM_SYNDROME_FRAGMENT_6_SYNDROME_VALID),
+		&elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6]);
+
+	/* wait for processing to complete */
+	while ((readl(&elm_cfg->irqstatus) & (0x1 << poly)) != 0x1)
+		;
+	/* clear status */
+	writel((readl(&elm_cfg->irqstatus) | (0x1 << poly)),
+			&elm_cfg->irqstatus);
+
+	/* check if correctable */
+	location_status = readl(&elm_cfg->error_location[poly].location_status);
+	if (!(location_status & ELM_LOCATION_STATUS_ECC_CORRECTABLE_MASK))
+		return -1;
+
+	/* get error count */
+	*error_count = readl(&elm_cfg->error_location[poly].location_status) &
+					ELM_LOCATION_STATUS_ECC_NB_ERRORS_MASK;
+
+	for (i = 0; i < *error_count; i++) {
+		error_locations[i] =
+			readl(&elm_cfg->error_location[poly].error_location_x[i]);
+	}
+
+	return 0;
+}
+
+
+/**
+ * elm_config - Configure ELM module
+ * @level: 4 / 8 / 16 bit BCH
+ *
+ * Configure ELM module based on BCH level.
+ * Set mode as continuous mode.
+ * Currently we are using only syndrome 0 and syndromes 1 to 6 are not used.
+ * Also, the mode is set only for syndrome 0
+ */
+int elm_config(enum bch_level level)
+{
+	u32 val;
+	u8 poly = ELM_DEFAULT_POLY;
+	u32 buffer_size = 0x7FF;
+
+	/* config size and level */
+	val = (u32)(level) & ELM_LOCATION_CONFIG_ECC_BCH_LEVEL_MASK;
+	val |= ((buffer_size << ELM_LOCATION_CONFIG_ECC_SIZE_POS) &
+				ELM_LOCATION_CONFIG_ECC_SIZE_MASK);
+	writel(val, &elm_cfg->location_config);
+
+	/* config continous mode */
+	/* enable interrupt generation for syndrome polynomial set */
+	writel((readl(&elm_cfg->irqenable) | (0x1 << poly)),
+			&elm_cfg->irqenable);
+	/* set continuous mode for the syndrome polynomial set */
+	writel((readl(&elm_cfg->page_ctrl) & ~(0x1 << poly)),
+			&elm_cfg->page_ctrl);
+
+	return 0;
+}
+
+/**
+ * elm_reset - Do a soft reset of ELM
+ *
+ * Perform a soft reset of ELM and return after reset is done.
+ */
+void elm_reset(void)
+{
+	/* initiate reset */
+	writel((readl(&elm_cfg->sysconfig) | ELM_SYSCONFIG_SOFTRESET),
+				&elm_cfg->sysconfig);
+
+	/* wait for reset complete and normal operation */
+	while ((readl(&elm_cfg->sysstatus) & ELM_SYSSTATUS_RESETDONE) !=
+		ELM_SYSSTATUS_RESETDONE)
+		;
+}
+
+/**
+ * elm_init - Initialize ELM module
+ *
+ * Initialize ELM support. Currently it does only base address init
+ * and ELM reset.
+ */
+void elm_init(void)
+{
+	elm_cfg = (struct elm *)ELM_BASE;
+	elm_reset();
+}

arch/arm/include/asm/arch-am33xx/elm.h

@@ -0,0 +1,93 @@
+/*
+ * (C) Copyright 2010-2011 Texas Instruments, <www.ti.com>
+ * Mansoor Ahamed <mansoor.ahamed@ti.com>
+ *
+ * Derived from work done by Rohit Choraria <rohitkc@ti.com> for omap3
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+#ifndef __ASM_ARCH_ELM_H
+#define __ASM_ARCH_ELM_H
+/*
+ * ELM Module Registers
+ */
+
+/* ELM registers bit fields */
+#define ELM_SYSCONFIG_SOFTRESET_MASK			(0x2)
+#define ELM_SYSCONFIG_SOFTRESET			(0x2)
+#define ELM_SYSSTATUS_RESETDONE_MASK			(0x1)
+#define ELM_SYSSTATUS_RESETDONE			(0x1)
+#define ELM_LOCATION_CONFIG_ECC_BCH_LEVEL_MASK		(0x3)
+#define ELM_LOCATION_CONFIG_ECC_SIZE_MASK		(0x7FF0000)
+#define ELM_LOCATION_CONFIG_ECC_SIZE_POS		(16)
+#define ELM_SYNDROME_FRAGMENT_6_SYNDROME_VALID		(0x00010000)
+#define ELM_LOCATION_STATUS_ECC_CORRECTABLE_MASK	(0x100)
+#define ELM_LOCATION_STATUS_ECC_NB_ERRORS_MASK		(0x1F)
+
+#ifndef __ASSEMBLY__
+
+enum bch_level {
+	BCH_4_BIT = 0,
+	BCH_8_BIT,
+	BCH_16_BIT
+};
+
+
+/* BCH syndrome registers */
+struct syndrome {
+	u32 syndrome_fragment_x[7];	/* 0x400, 0x404.... 0x418 */
+	u8 res1[36];			/* 0x41c */
+};
+
+/* BCH error status & location register */
+struct location {
+	u32 location_status;		/* 0x800 */
+	u8 res1[124];			/* 0x804 */
+	u32 error_location_x[16];	/* 0x880.... */
+	u8 res2[64];			/* 0x8c0 */
+};
+
+/* BCH ELM register map - do not try to allocate memmory for this structure.
+ * We have used plenty of reserved variables to fill the slots in the ELM
+ * register memory map.
+ * Directly initialize the struct pointer to ELM base address.
+ */
+struct elm {
+	u32 rev;				/* 0x000 */
+	u8 res1[12];				/* 0x004 */
+	u32 sysconfig;				/* 0x010 */
+	u32 sysstatus;				/* 0x014 */
+	u32 irqstatus;				/* 0x018 */
+	u32 irqenable;				/* 0x01c */
+	u32 location_config;			/* 0x020 */
+	u8 res2[92];				/* 0x024 */
+	u32 page_ctrl;				/* 0x080 */
+	u8 res3[892];				/* 0x084 */
+	struct  syndrome syndrome_fragments[8]; /* 0x400 */
+	u8 res4[512];				/* 0x600 */
+	struct location  error_location[8];	/* 0x800 */
+};
+
+int elm_check_error(u8 *syndrome, u32 nibbles, u32 *error_count,
+		u32 *error_locations);
+int elm_config(enum bch_level level);
+void elm_reset(void);
+void elm_init(void);
+#endif /* __ASSEMBLY__ */
+#endif /* __ASM_ARCH_ELM_H */