sf: Add SPI protection mechanism from the kernel

Add the SPI NOR protection mechanism from the kernel.

This code is based on the work from
Brian Norris <computersforpeace@gmail.com>
Here is the commit details:
"mtd: spi-nor: refactor block protection functions"
(sha1: 62593cf40b23b523b9fc9334ca61ba6c595ebb09)

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Jagan Teki <jteki@openedev.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Jagan Teki <jteki@openedev.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index 8a3e5ec3d7adb8a009aad758ef321e7d6399e391..ac493f1f76789a2a59fe9be7ed85bb54646f21f9 100644 (file)
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -105,6 +105,9 @@ enum spi_nor_option_flags {
 #define STATUS_QEB_WINSPAN             (1 << 1)
 #define STATUS_QEB_MXIC                (1 << 6)
 #define STATUS_PEC                     (1 << 7)
+#define SR_BP0                         BIT(2)  /* Block protect 0 */
+#define SR_BP1                         BIT(3)  /* Block protect 1 */
+#define SR_BP2                         BIT(4)  /* Block protect 2 */
 
 /* Flash timeout values */
 #define SPI_FLASH_PROG_TIMEOUT         (2 * CONFIG_SYS_HZ)

diff --git a/drivers/mtd/spi/sf_ops.c b/drivers/mtd/spi/sf_ops.c
index f2a9244a14e9d1e98acedf4e999a7b8949c82497..6c87ba60fde200939db73ed07e92a868bdc4825a 100644 (file)
--- 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"
 
@@ -565,3 +566,172 @@ 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, size_t 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, size_t 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 */