eeprom/spi_xx25xx: Add IOCTL to set Block Protect

Add IOCTL to set Block Protect, because we need a way to set Block
Protect of an EEPROM.

Signed-off-by: Jiri Vlasak <jvlasak@elektroline.cz>

Documentation/components/drivers/character/eeprom.rst

@@ -184,6 +184,17 @@ The full list of ``ioctl()`` commands can be found in
     Erase the full EEPROM, a dedicated command is used if supported by the
     device.
 
+- ``EEPIOC_BLOCKPROTECT``
+    *Argument:* ``uint8_t``
+
+    Set EEPROM's Block Protect bits. For 25AA160-compatible EEPROM with
+    two Block Protect bits in Status Register, the argument may be:
+
+    - ``0`` for no write protect,
+    - ``1`` to set Block Protection 0 bit of Status Register,
+    - ``2`` to set Block Protection 1 bit of Status Register,
+    - ``3`` to set both Block Protection bits 0 and 1.
+
 File Systems
 ============
 

drivers/eeprom/i2c_xx24xx.c

@@ -964,6 +964,8 @@ static int ee24xx_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
         ret = ee24xx_eraseall(eedev);
         break;
 
+      /* TODO: add "case EEPIOC_BLOCKPROTECT:" */
+
       default:
         ret = -ENOTTY;
     }

drivers/eeprom/spi_xx25xx.c

@@ -731,6 +731,50 @@ static int ee25xx_erasesector(FAR struct ee25xx_dev_s *eedev,
   return ret;
 }
 
+/****************************************************************************
+ * Name: ee25xx_rdsr
+ *
+ * Description: Read status register.
+ *
+ ****************************************************************************/
+
+static uint8_t ee25xx_rdsr(FAR struct ee25xx_dev_s *eedev)
+{
+  uint8_t tx[2];
+  uint8_t rx[2];
+
+  tx[0] = EE25XX_CMD_RDSR;
+  tx[1] = EE25XX_DUMMY;
+
+  ee25xx_lock(eedev);
+  SPI_SELECT(eedev->spi, SPIDEV_EEPROM(eedev->devid), true);
+  SPI_EXCHANGE(eedev->spi, tx, rx, 2);
+  SPI_SELECT(eedev->spi, SPIDEV_EEPROM(eedev->devid), false);
+  ee25xx_unlock(eedev);
+  return rx[1];
+}
+
+/****************************************************************************
+ * Name: ee25xx_wrsr
+ *
+ * Description: Write status register.
+ *
+ ****************************************************************************/
+
+static void ee25xx_wrsr(FAR struct ee25xx_dev_s *eedev, uint8_t what)
+{
+  uint8_t tx[2];
+
+  tx[0] = EE25XX_CMD_WRSR;
+  tx[1] = what;
+
+  ee25xx_lock(eedev);
+  SPI_SELECT(eedev->spi, SPIDEV_EEPROM(eedev->devid), true);
+  SPI_EXCHANGE(eedev->spi, tx, NULL, 2);
+  SPI_SELECT(eedev->spi, SPIDEV_EEPROM(eedev->devid), false);
+  ee25xx_unlock(eedev);
+}
+
 /****************************************************************************
  * Driver Functions
  ****************************************************************************/
@@ -1094,6 +1138,29 @@ static int ee25xx_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
         ret = ee25xx_eraseall(eedev);
         break;
 
+      case EEPIOC_BLOCKPROTECT:
+        {
+          /* Get current value of status register. */
+
+          ret = ee25xx_rdsr(eedev);
+
+          /* Clear Block Protection bits. */
+
+          ret &= ~(EE25XX_SR_BP0 | EE25XX_SR_BP1);
+
+          /* Set Block Protection bits. */
+
+          ret |= ((uint8_t)arg << 2) & (EE25XX_SR_BP0 | EE25XX_SR_BP1);
+
+          /* Write status register. */
+
+          ee25xx_writeenable(eedev, true);
+          ee25xx_wrsr(eedev, ret);
+          ee25xx_waitwritecomplete(eedev);
+          ret = OK;
+        }
+        break;
+
       default:
         ret = -ENOTTY;
     }

include/nuttx/eeprom/eeprom.h

@@ -84,6 +84,11 @@
                                              *      provides success/failure
                                              *      indication).            */
 
+#define EEPIOC_BLOCKPROTECT _EEPIOC(0x005)  /* Set which memory blocks to
+                                             * protect.
+                                             * IN:  Which blocks as integer.
+                                             * OUT: OK (0) on success.      */
+
 /************************************************************************************
  * Type Definitions
  ************************************************************************************/