[U-Boot] [PATCH v8 3/4] spi: sf_ops: Add SPI protection mechanism from the kernel
Fabio Estevam
festevam at gmail.com
Fri Oct 16 22:41:14 CEST 2015
From: Fabio Estevam <fabio.estevam at freescale.com>
Add the SPI NOR protection mechanism from the kernel.
This code is based on the work from Brian Norris <computersforpeace at gmail.com>
https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/drivers/mtd/spi-nor/spi-nor.c?id=62593cf40b23b523b9fc9334ca61ba6c595ebb09
Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
---
Changes since v7:
- Move BP macros to header file (Jagan)
- Remove else block (Jagan)
drivers/mtd/spi/sf_ops.c | 170 +++++++++++++++++++++++++++++++++++++++++++++++
include/spi_flash.h | 4 ++
2 files changed, 174 insertions(+)
diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c
index 900ec1f..928f9c1 100644
--- a/drivers/mtd/spi/sf_ops.c
+++ b/drivers/mtd/spi/sf_ops.c
@@ -15,6 +15,7 @@
#include <spi_flash.h>
#include <watchdog.h>
#include <linux/compiler.h>
+#include <linux/log2.h>
#include "sf_internal.h"
@@ -573,3 +574,172 @@ int sst_write_bp(struct spi_flash *flash, u32 offset, size_t len,
return ret;
}
#endif
+
+#ifdef CONFIG_SPI_FLASH_STMICRO
+static void stm_get_locked_range(struct spi_flash *flash, u8 sr, loff_t *ofs,
+ u32 *len)
+{
+ u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
+ int shift = ffs(mask) - 1;
+ int pow;
+
+ if (!(sr & mask)) {
+ /* No protection */
+ *ofs = 0;
+ *len = 0;
+ } else {
+ pow = ((sr & mask) ^ mask) >> shift;
+ *len = flash->size >> pow;
+ *ofs = flash->size - *len;
+ }
+}
+
+/*
+ * Return 1 if the entire region is locked, 0 otherwise
+ */
+static int stm_is_locked_sr(struct spi_flash *flash, loff_t ofs, u32 len,
+ u8 sr)
+{
+ loff_t lock_offs;
+ u32 lock_len;
+
+ stm_get_locked_range(flash, sr, &lock_offs, &lock_len);
+
+ return (ofs + len <= lock_offs + lock_len) && (ofs >= lock_offs);
+}
+
+/*
+ * Check if a region of the flash is (completely) locked. See stm_lock() for
+ * more info.
+ *
+ * Returns 1 if entire region is locked, 0 if any portion is unlocked, and
+ * negative on errors.
+ */
+int stm_is_locked(struct spi_flash *flash, loff_t ofs, u32 len)
+{
+ int status;
+ u8 sr;
+
+ status = spi_flash_cmd_read_status(flash, &sr);
+ if (status < 0)
+ return status;
+
+ return stm_is_locked_sr(flash, ofs, len, sr);
+}
+
+/*
+ * Lock a region of the flash. Compatible with ST Micro and similar flash.
+ * Supports only the block protection bits BP{0,1,2} in the status register
+ * (SR). Does not support these features found in newer SR bitfields:
+ * - TB: top/bottom protect - only handle TB=0 (top protect)
+ * - SEC: sector/block protect - only handle SEC=0 (block protect)
+ * - CMP: complement protect - only support CMP=0 (range is not complemented)
+ *
+ * Sample table portion for 8MB flash (Winbond w25q64fw):
+ *
+ * SEC | TB | BP2 | BP1 | BP0 | Prot Length | Protected Portion
+ * --------------------------------------------------------------------------
+ * X | X | 0 | 0 | 0 | NONE | NONE
+ * 0 | 0 | 0 | 0 | 1 | 128 KB | Upper 1/64
+ * 0 | 0 | 0 | 1 | 0 | 256 KB | Upper 1/32
+ * 0 | 0 | 0 | 1 | 1 | 512 KB | Upper 1/16
+ * 0 | 0 | 1 | 0 | 0 | 1 MB | Upper 1/8
+ * 0 | 0 | 1 | 0 | 1 | 2 MB | Upper 1/4
+ * 0 | 0 | 1 | 1 | 0 | 4 MB | Upper 1/2
+ * X | X | 1 | 1 | 1 | 8 MB | ALL
+ *
+ * Returns negative on errors, 0 on success.
+ */
+int stm_lock(struct spi_flash *flash, u32 ofs, u32 len)
+{
+ u8 status_old, status_new;
+ u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
+ u8 shift = ffs(mask) - 1, pow, val;
+
+ spi_flash_cmd_read_status(flash, &status_old);
+
+ /* SPI NOR always locks to the end */
+ if (ofs + len != flash->size) {
+ /* Does combined region extend to end? */
+ if (!stm_is_locked_sr(flash, ofs + len, flash->size - ofs - len,
+ status_old))
+ return -EINVAL;
+ len = flash->size - ofs;
+ }
+
+ /*
+ * Need smallest pow such that:
+ *
+ * 1 / (2^pow) <= (len / size)
+ *
+ * so (assuming power-of-2 size) we do:
+ *
+ * pow = ceil(log2(size / len)) = log2(size) - floor(log2(len))
+ */
+ pow = ilog2(flash->size) - ilog2(len);
+ val = mask - (pow << shift);
+ if (val & ~mask)
+ return -EINVAL;
+
+ /* Don't "lock" with no region! */
+ if (!(val & mask))
+ return -EINVAL;
+
+ status_new = (status_old & ~mask) | val;
+
+ /* Only modify protection if it will not unlock other areas */
+ if ((status_new & mask) <= (status_old & mask))
+ return -EINVAL;
+
+ spi_flash_cmd_write_status(flash, status_new);
+
+ return 0;
+}
+
+/*
+ * Unlock a region of the flash. See stm_lock() for more info
+ *
+ * Returns negative on errors, 0 on success.
+ */
+int stm_unlock(struct spi_flash *flash, u32 ofs, u32 len)
+{
+ uint8_t status_old, status_new;
+ u8 mask = SR_BP2 | SR_BP1 | SR_BP0;
+ u8 shift = ffs(mask) - 1, pow, val;
+
+ spi_flash_cmd_read_status(flash, &status_old);
+
+ /* Cannot unlock; would unlock larger region than requested */
+ if (stm_is_locked_sr(flash, status_old, ofs - flash->erase_size,
+ flash->erase_size))
+ return -EINVAL;
+ /*
+ * Need largest pow such that:
+ *
+ * 1 / (2^pow) >= (len / size)
+ *
+ * so (assuming power-of-2 size) we do:
+ *
+ * pow = floor(log2(size / len)) = log2(size) - ceil(log2(len))
+ */
+ pow = ilog2(flash->size) - order_base_2(flash->size - (ofs + len));
+ if (ofs + len == flash->size) {
+ val = 0; /* fully unlocked */
+ } else {
+ val = mask - (pow << shift);
+ /* Some power-of-two sizes are not supported */
+ if (val & ~mask)
+ return -EINVAL;
+ }
+
+ status_new = (status_old & ~mask) | val;
+
+ /* Only modify protection if it will not lock other areas */
+ if ((status_new & mask) >= (status_old & mask))
+ return -EINVAL;
+
+ spi_flash_cmd_write_status(flash, status_new);
+
+ return 0;
+}
+#endif /* CONFIG_SPI_FLASH_STMICRO */
diff --git a/include/spi_flash.h b/include/spi_flash.h
index 3b2d555..73b2b0a 100644
--- a/include/spi_flash.h
+++ b/include/spi_flash.h
@@ -31,6 +31,10 @@
# define CONFIG_SF_DEFAULT_BUS 0
#endif
+#define SR_BP0 BIT(2) /* Block protect 0 */
+#define SR_BP1 BIT(3) /* Block protect 1 */
+#define SR_BP2 BIT(4) /* Block protect 2 */
+
struct spi_slave;
/**
--
1.9.1
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