mfd: Add a prcmu_abb_write_masked routine to db8500-prcmu

This patch adds driver support for the I2C read-modify-write
service in the U8500 PRCMU firmware.
Signed-off-by: Mattias Nilsson <mattias.i.nilsson@stericsson.com>
Reviewed-by: Jonas ABERG <jonas.aberg@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/db8500-prcmu.c

@@ -2332,6 +2332,7 @@ int prcmu_abb_read(u8 slave, u8 reg, u8 *value, u8 size)
 	while (readl(PRCM_MBOX_CPU_VAL) & MBOX_BIT(5))
 		cpu_relax();
 
+	writeb(0, (tcdm_base + PRCM_MBOX_HEADER_REQ_MB5));
 	writeb(PRCMU_I2C_READ(slave), (tcdm_base + PRCM_REQ_MB5_I2C_SLAVE_OP));
 	writeb(PRCMU_I2C_STOP_EN, (tcdm_base + PRCM_REQ_MB5_I2C_HW_BITS));
 	writeb(reg, (tcdm_base + PRCM_REQ_MB5_I2C_REG));
@@ -2357,16 +2358,19 @@ int prcmu_abb_read(u8 slave, u8 reg, u8 *value, u8 size)
 }
 
 /**
- * prcmu_abb_write() - Write register value(s) to the ABB.
+ * prcmu_abb_write_masked() - Write masked register value(s) to the ABB.
  * @slave:	The I2C slave address.
  * @reg:	The (start) register address.
  * @value:	The value(s) to write.
+ * @mask:	The mask(s) to use.
  * @size:	The number of registers to write.
  *
- * Reads register value(s) from the ABB.
+ * Writes masked register value(s) to the ABB.
+ * For each @value, only the bits set to 1 in the corresponding @mask
+ * will be written. The other bits are not changed.
  * @size has to be 1 for the current firmware version.
  */
-int prcmu_abb_write(u8 slave, u8 reg, u8 *value, u8 size)
+int prcmu_abb_write_masked(u8 slave, u8 reg, u8 *value, u8 *mask, u8 size)
 {
 	int r;
 
@@ -2378,6 +2382,7 @@ int prcmu_abb_write(u8 slave, u8 reg, u8 *value, u8 size)
 	while (readl(PRCM_MBOX_CPU_VAL) & MBOX_BIT(5))
 		cpu_relax();
 
+	writeb(~*mask, (tcdm_base + PRCM_MBOX_HEADER_REQ_MB5));
 	writeb(PRCMU_I2C_WRITE(slave), (tcdm_base + PRCM_REQ_MB5_I2C_SLAVE_OP));
 	writeb(PRCMU_I2C_STOP_EN, (tcdm_base + PRCM_REQ_MB5_I2C_HW_BITS));
 	writeb(reg, (tcdm_base + PRCM_REQ_MB5_I2C_REG));
@@ -2399,6 +2404,23 @@ int prcmu_abb_write(u8 slave, u8 reg, u8 *value, u8 size)
 	return r;
 }
 
+/**
+ * prcmu_abb_write() - Write register value(s) to the ABB.
+ * @slave:	The I2C slave address.
+ * @reg:	The (start) register address.
+ * @value:	The value(s) to write.
+ * @size:	The number of registers to write.
+ *
+ * Writes register value(s) to the ABB.
+ * @size has to be 1 for the current firmware version.
+ */
+int prcmu_abb_write(u8 slave, u8 reg, u8 *value, u8 size)
+{
+	u8 mask = ~0;
+
+	return prcmu_abb_write_masked(slave, reg, value, &mask, size);
+}
+
 /**
  * prcmu_ac_wake_req - should be called whenever ARM wants to wakeup Modem
  */

include/linux/mfd/dbx500-prcmu.h

@@ -368,6 +368,7 @@ static inline void prcmu_get_abb_event_buffer(void __iomem **buf)
 
 int prcmu_abb_read(u8 slave, u8 reg, u8 *value, u8 size);
 int prcmu_abb_write(u8 slave, u8 reg, u8 *value, u8 size);
+int prcmu_abb_write_masked(u8 slave, u8 reg, u8 *value, u8 *mask, u8 size);
 
 int prcmu_config_clkout(u8 clkout, u8 source, u8 div);
 
@@ -620,6 +621,12 @@ static inline int prcmu_abb_write(u8 slave, u8 reg, u8 *value, u8 size)
 	return -ENOSYS;
 }
 
+static inline int prcmu_abb_write_masked(u8 slave, u8 reg, u8 *value, u8 *mask,
+	u8 size)
+{
+	return -ENOSYS;
+}
+
 static inline int prcmu_config_clkout(u8 clkout, u8 source, u8 div)
 {
 	return 0;