mtd: sf: Add support of sst26wf* flash ICs protection ops

sst26wf flash series block protection implementation differs
from other SST series, so add specific implementation
flash_lock/flash_unlock/flash_is_locked functions for sst26wf
flash ICs.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

2 files changed, 181 insertions, 0 deletions

diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index 839cdbe1b0f..614a293234e 100644
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -87,6 +87,19 @@ enum spi_nor_option_flags {
 
 /* SST specific */
 #ifdef CONFIG_SPI_FLASH_SST
+#define SST26_CMD_READ_BPR		0x72
+#define SST26_CMD_WRITE_BPR		0x42
+
+#define SST26_BPR_8K_NUM		4
+#define SST26_MAX_BPR_REG_LEN		(18 + 1)
+#define SST26_BOUND_REG_SIZE		((32 + SST26_BPR_8K_NUM * 8) * SZ_1K)
+
+enum lock_ctl {
+	SST26_CTL_LOCK,
+	SST26_CTL_UNLOCK,
+	SST26_CTL_CHECK
+};
+
 # define CMD_SST_BP		0x02    /* Byte Program */
 # define CMD_SST_AAI_WP		0xAD	/* Auto Address Incr Word Program */
 
diff --git a/drivers/mtd/spi/spi_flash.c b/drivers/mtd/spi/spi_flash.c
index 2e61685d3ea..5e5bd5d5336 100644
--- a/drivers/mtd/spi/spi_flash.c
+++ b/drivers/mtd/spi/spi_flash.c
@@ -16,6 +16,7 @@
 #include <spi.h>
 #include <spi_flash.h>
 #include <linux/log2.h>
+#include <linux/sizes.h>
 #include <dma.h>
 
 #include "sf_internal.h"
@@ -541,6 +542,164 @@ int spi_flash_cmd_read_ops(struct spi_flash *flash, u32 offset,
 }
 
 #ifdef CONFIG_SPI_FLASH_SST
+static bool sst26_process_bpr(u32 bpr_size, u8 *cmd, u32 bit, enum lock_ctl ctl)
+{
+	switch (ctl) {
+		case SST26_CTL_LOCK:
+			cmd[bpr_size - (bit / 8) - 1] |= BIT(bit % 8);
+			break;
+		case SST26_CTL_UNLOCK:
+			cmd[bpr_size - (bit / 8) - 1] &= ~BIT(bit % 8);
+			break;
+		case SST26_CTL_CHECK:
+			return !!(cmd[bpr_size - (bit / 8) - 1] & BIT(bit % 8));
+	}
+
+	return false;
+}
+
+/*
+ * sst26wf016/sst26wf032/sst26wf064 have next block protection:
+ * 4x   - 8  KByte blocks - read & write protection bits - upper addresses
+ * 1x   - 32 KByte blocks - write protection bits
+ * rest - 64 KByte blocks - write protection bits
+ * 1x   - 32 KByte blocks - write protection bits
+ * 4x   - 8  KByte blocks - read & write protection bits - lower addresses
+ *
+ * We'll support only per 64k lock/unlock so lower and upper 64 KByte region
+ * will be treated as single block.
+ */
+
+/*
+ * Lock, unlock or check lock status of the flash region of the flash (depending
+ * on the lock_ctl value)
+ */
+static int sst26_lock_ctl(struct spi_flash *flash, u32 ofs, size_t len, enum lock_ctl ctl)
+{
+	u32 i, bpr_ptr, rptr_64k, lptr_64k, bpr_size;
+	bool lower_64k = false, upper_64k = false;
+	u8 cmd, bpr_buff[SST26_MAX_BPR_REG_LEN] = {};
+	int ret;
+
+	/* Check length and offset for 64k alignment */
+	if ((ofs & (SZ_64K - 1)) || (len & (SZ_64K - 1)))
+		return -EINVAL;
+
+	if (ofs + len > flash->size)
+		return -EINVAL;
+
+	/* SST26 family has only 16 Mbit, 32 Mbit and 64 Mbit IC */
+	if (flash->size != SZ_2M &&
+	    flash->size != SZ_4M &&
+	    flash->size != SZ_8M)
+		return -EINVAL;
+
+	bpr_size = 2 + (flash->size / SZ_64K / 8);
+
+	cmd = SST26_CMD_READ_BPR;
+	ret = spi_flash_read_common(flash, &cmd, 1, bpr_buff, bpr_size);
+	if (ret < 0) {
+		printf("SF: fail to read block-protection register\n");
+		return ret;
+	}
+
+	rptr_64k = min_t(u32, ofs + len , flash->size - SST26_BOUND_REG_SIZE);
+	lptr_64k = max_t(u32, ofs, SST26_BOUND_REG_SIZE);
+
+	upper_64k = ((ofs + len) > (flash->size - SST26_BOUND_REG_SIZE));
+	lower_64k = (ofs < SST26_BOUND_REG_SIZE);
+
+	/* Lower bits in block-protection register are about 64k region */
+	bpr_ptr = lptr_64k / SZ_64K - 1;
+
+	/* Process 64K blocks region */
+	while (lptr_64k < rptr_64k) {
+		if (sst26_process_bpr(bpr_size, bpr_buff, bpr_ptr, ctl))
+			return EACCES;
+
+		bpr_ptr++;
+		lptr_64k += SZ_64K;
+	}
+
+	/* 32K and 8K region bits in BPR are after 64k region bits */
+	bpr_ptr = (flash->size - 2 * SST26_BOUND_REG_SIZE) / SZ_64K;
+
+	/* Process lower 32K block region */
+	if (lower_64k)
+		if (sst26_process_bpr(bpr_size, bpr_buff, bpr_ptr, ctl))
+			return EACCES;
+
+	bpr_ptr++;
+
+	/* Process upper 32K block region */
+	if (upper_64k)
+		if (sst26_process_bpr(bpr_size, bpr_buff, bpr_ptr, ctl))
+			return EACCES;
+
+	bpr_ptr++;
+
+	/* Process lower 8K block regions */
+	for (i = 0; i < SST26_BPR_8K_NUM; i++) {
+		if (lower_64k)
+			if (sst26_process_bpr(bpr_size, bpr_buff, bpr_ptr, ctl))
+				return EACCES;
+
+		/* In 8K area BPR has both read and write protection bits */
+		bpr_ptr += 2;
+	}
+
+	/* Process upper 8K block regions */
+	for (i = 0; i < SST26_BPR_8K_NUM; i++) {
+		if (upper_64k)
+			if (sst26_process_bpr(bpr_size, bpr_buff, bpr_ptr, ctl))
+				return EACCES;
+
+		/* In 8K area BPR has both read and write protection bits */
+		bpr_ptr += 2;
+	}
+
+	/* If we check region status we don't need to write BPR back */
+	if (ctl == SST26_CTL_CHECK)
+		return 0;
+
+	cmd = SST26_CMD_WRITE_BPR;
+	ret = spi_flash_write_common(flash, &cmd, 1, bpr_buff, bpr_size);
+	if (ret < 0) {
+		printf("SF: fail to write block-protection register\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int sst26_unlock(struct spi_flash *flash, u32 ofs, size_t len)
+{
+	return sst26_lock_ctl(flash, ofs, len, SST26_CTL_UNLOCK);
+}
+
+static int sst26_lock(struct spi_flash *flash, u32 ofs, size_t len)
+{
+	return sst26_lock_ctl(flash, ofs, len, SST26_CTL_LOCK);
+}
+
+/*
+ * Returns EACCES (positive value) if region is locked, 0 if region is unlocked,
+ * and negative on errors.
+ */
+static int sst26_is_locked(struct spi_flash *flash, u32 ofs, size_t len)
+{
+	/*
+	 * is_locked function is used for check before reading or erasing flash
+	 * region, so offset and length might be not 64k allighned, so adjust
+	 * them to be 64k allighned as sst26_lock_ctl works only with 64k
+	 * allighned regions.
+	 */
+	ofs -= ofs & (SZ_64K - 1);
+	len = len & (SZ_64K - 1) ? (len & ~(SZ_64K - 1)) + SZ_64K : len;
+
+	return sst26_lock_ctl(flash, ofs, len, SST26_CTL_CHECK);
+}
+
 static int sst_byte_write(struct spi_flash *flash, u32 offset, const void *buf)
 {
 	struct spi_slave *spi = flash->spi;
@@ -1033,6 +1192,15 @@ int spi_flash_scan(struct spi_flash *flash)
 	}
 #endif
 
+/* sst26wf series block protection implementation differs from other series */
+#if defined(CONFIG_SPI_FLASH_SST)
+	if (JEDEC_MFR(info) == SPI_FLASH_CFI_MFR_SST && info->id[1] == 0x26) {
+		flash->flash_lock = sst26_lock;
+		flash->flash_unlock = sst26_unlock;
+		flash->flash_is_locked = sst26_is_locked;
+	}
+#endif
+
 	/* Compute the flash size */
 	flash->shift = (flash->dual_flash & SF_DUAL_PARALLEL_FLASH) ? 1 : 0;
 	flash->page_size = info->page_size;