i2c: add generic read/modify/write operations

i2c_update is used to set or clear a mask
i2c_field_update is used to clear out a field before the set

BUG=none
BRANCH=none
TEST=make buildall -j

Change-Id: I7f8f93f4894fb9635092931a93961d328eacfeb9
Signed-off-by: Denis Brockus <dbrockus@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1956437
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Jett Rink <jettrink@chromium.org>
Commit-Queue: Jett Rink <jettrink@chromium.org>

2 files changed, 137 insertions, 0 deletions

diff --git a/common/i2c_master.c b/common/i2c_master.c
index d89e20b920..beae1323e4 100644
--- a/common/i2c_master.c
+++ b/common/i2c_master.c
@@ -425,6 +425,92 @@ int i2c_write8(const int port,
 	return i2c_write(port, slave_addr_flags, buf, sizeof(buf));
 }
 
+int i2c_update8(const int port,
+		const uint16_t slave_addr_flags,
+		const int offset,
+		const uint8_t mask,
+		const enum mask_update_action action)
+{
+	int rv;
+	int val, oldval;
+
+	rv = i2c_read8(port, slave_addr_flags, offset, &oldval);
+	if (rv)
+		return rv;
+
+	val = (action == MASK_SET) ? oldval | mask
+				   : oldval & ~mask;
+
+	if (val != oldval)
+		return i2c_write8(port, slave_addr_flags, offset, val);
+
+	return EC_SUCCESS;
+}
+
+int i2c_update16(const int port,
+		 const uint16_t slave_addr_flags,
+		 const int offset,
+		 const uint16_t mask,
+		 const enum mask_update_action action)
+{
+	int rv;
+	int val, oldval;
+
+	rv = i2c_read16(port, slave_addr_flags, offset, &oldval);
+	if (rv)
+		return rv;
+
+	val = (action == MASK_SET) ? oldval | mask
+				   : oldval & ~mask;
+
+	if (val != oldval)
+		return i2c_write16(port, slave_addr_flags, offset, val);
+
+	return EC_SUCCESS;
+}
+
+int i2c_field_update8(const int port,
+		      const uint16_t slave_addr_flags,
+		      const int offset,
+		      const uint8_t field_mask,
+		      const uint8_t set_value)
+{
+	int rv;
+	int val, oldval;
+
+	rv = i2c_read8(port, slave_addr_flags, offset, &oldval);
+	if (rv)
+		return rv;
+
+	val = (oldval & (~field_mask)) | set_value;
+
+	if (val != oldval)
+		return i2c_write8(port, slave_addr_flags, offset, val);
+
+	return EC_SUCCESS;
+}
+
+int i2c_field_update16(const int port,
+		       const uint16_t slave_addr_flags,
+		       const int offset,
+		       const uint16_t field_mask,
+		       const uint16_t set_value)
+{
+	int rv;
+	int val, oldval;
+
+	rv = i2c_read16(port, slave_addr_flags, offset, &oldval);
+	if (rv)
+		return rv;
+
+	val = (oldval & (~field_mask)) | set_value;
+
+	if (val != oldval)
+		return i2c_write16(port, slave_addr_flags, offset, val);
+
+	return EC_SUCCESS;
+}
+
 int i2c_read_offset16(const int port,
 		      const uint16_t slave_addr_flags,
 		      uint16_t offset, int *data, int len)
diff --git a/include/i2c.h b/include/i2c.h
index 4be5472a11..bca96536b9 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -77,6 +77,16 @@ enum i2c_freq {
 	I2C_FREQ_COUNT,
 };
 
+/*
+ * I2C mask update actions.
+ *      MASK_SET will OR the mask into the old value
+ *      MASK_CLR will AND the ~mask from the old value
+ */
+enum mask_update_action {
+	MASK_CLR,
+	MASK_SET
+};
+
 struct i2c_info_t {
 	uint16_t port;	/* Physical port for device */
 	uint16_t addr_flags;
@@ -335,6 +345,47 @@ int i2c_write8(const int port,
 	       int offset, int data);
 
 /**
+ * Read, modify, write an i2c register to the slave at 7-bit slave address
+ * <slave_addr_flags>, at the specified 8-bit <offset> in the slave's
+ * address space.  The <action> will specify whether this is setting the
+ * <mask> bit value(s) or clearing them. If the value to be written is the
+ * same as the original value of the register, the write will not be
+ * performed.
+ */
+int i2c_update8(const int port,
+		const uint16_t slave_addr_flags,
+		const int offset,
+		const uint8_t mask,
+		const enum mask_update_action action);
+
+int i2c_update16(const int port,
+		 const uint16_t slave_addr_flags,
+		 const int offset,
+		 const uint16_t mask,
+		 const enum mask_update_action action);
+
+/**
+ * Read, modify, write field of an i2c register to the slave at 7-bit
+ * slave address <slave_addr_flags>, at the specified 8-bit <offset> in
+ * the slave's address space.  The register will be read, the <field_mask>
+ * will be cleared and then the <set_value> will be set.  The field mask
+ * and the set value do not have to be in the same bit locations.  If the
+ * new value is not the same as the original value, the new value will be
+ * written back out to the device, otherwise no write will be performed.
+ */
+int i2c_field_update8(const int port,
+		      const uint16_t slave_addr_flags,
+		      const int offset,
+		      const uint8_t field_mask,
+		      const uint8_t set_value);
+
+int i2c_field_update16(const int port,
+		       const uint16_t slave_addr_flags,
+		       const int offset,
+		       const uint16_t field_mask,
+		       const uint16_t set_value);
+
+/**
  * Read one or two bytes data from the slave at 7-bit slave address
  * * <slaveaddr>, at 16-bit <offset> in the slave's address space.
  */