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path: root/drivers/i2c/mvtwsi.c
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Diffstat (limited to 'drivers/i2c/mvtwsi.c')
-rw-r--r--drivers/i2c/mvtwsi.c83
1 files changed, 41 insertions, 42 deletions
diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c
index 7b2c611..4a34eab 100644
--- a/drivers/i2c/mvtwsi.c
+++ b/drivers/i2c/mvtwsi.c
@@ -124,6 +124,17 @@ enum mvstwsi_status_values {
};
/*
+ * enum mvstwsi_ack_flags - Determine whether a read byte should be
+ * acknowledged or not.
+ */
+enum mvtwsi_ack_flags {
+ /* Send NAK after received byte */
+ MVTWSI_READ_NAK = 0,
+ /* Send ACK after received byte */
+ MVTWSI_READ_ACK = 1,
+};
+
+/*
* MVTWSI controller base
*/
@@ -225,14 +236,12 @@ static int twsi_wait(struct i2c_adapter *adap, int expected_status)
* Assert the START condition, either in a single I2C transaction
* or inside back-to-back ones (repeated starts).
*/
-static int twsi_start(struct i2c_adapter *adap, int expected_status, u8 *flags)
+static int twsi_start(struct i2c_adapter *adap, int expected_status)
{
struct mvtwsi_registers *twsi = twsi_get_base(adap);
- /* Set TWSIEN */
- *flags |= MVTWSI_CONTROL_TWSIEN;
/* Assert START */
- writel(*flags | MVTWSI_CONTROL_START |
+ writel(MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_START |
MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
/* Wait for controller to process START */
return twsi_wait(adap, expected_status);
@@ -241,15 +250,15 @@ static int twsi_start(struct i2c_adapter *adap, int expected_status, u8 *flags)
/*
* Send a byte (i2c address or data).
*/
-static int twsi_send(struct i2c_adapter *adap, u8 byte, int expected_status,
- u8 *flags)
+static int twsi_send(struct i2c_adapter *adap, u8 byte, int expected_status)
{
struct mvtwsi_registers *twsi = twsi_get_base(adap);
/* Write byte to data register for sending */
writel(byte, &twsi->data);
/* Clear any pending interrupt -- that will cause sending */
- writel(*flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
+ writel(MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_CLEAR_IFLG,
+ &twsi->control);
/* Wait for controller to receive byte, and check ACK */
return twsi_wait(adap, expected_status);
}
@@ -257,18 +266,18 @@ static int twsi_send(struct i2c_adapter *adap, u8 byte, int expected_status,
/*
* Receive a byte.
*/
-static int twsi_recv(struct i2c_adapter *adap, u8 *byte, u8 *flags)
+static int twsi_recv(struct i2c_adapter *adap, u8 *byte, int ack_flag)
{
struct mvtwsi_registers *twsi = twsi_get_base(adap);
- int expected_status, status;
+ int expected_status, status, control;
- /* Compute expected status based on ACK bit in passed control flags */
- if (*flags & MVTWSI_CONTROL_ACK)
- expected_status = MVTWSI_STATUS_DATA_R_ACK;
- else
- expected_status = MVTWSI_STATUS_DATA_R_NAK;
+ /* Compute expected status based on passed ACK flag */
+ expected_status = ack_flag ? MVTWSI_STATUS_DATA_R_ACK :
+ MVTWSI_STATUS_DATA_R_NAK;
/* Acknowledge *previous state*, and launch receive */
- writel(*flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
+ control = MVTWSI_CONTROL_TWSIEN;
+ control |= ack_flag == MVTWSI_READ_ACK ? MVTWSI_CONTROL_ACK : 0;
+ writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
/* Wait for controller to receive byte, and assert ACK or NAK */
status = twsi_wait(adap, expected_status);
/* If we did receive the expected byte, store it */
@@ -378,7 +387,7 @@ static void twsi_i2c_init(struct i2c_adapter *adap, int speed, int slaveadd)
* Expected address status will derive from direction bit (bit 0) in addr.
*/
static int i2c_begin(struct i2c_adapter *adap, int expected_start_status,
- u8 addr, u8 *flags)
+ u8 addr)
{
int status, expected_addr_status;
@@ -389,11 +398,10 @@ static int i2c_begin(struct i2c_adapter *adap, int expected_start_status,
else /* Writing */
expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK;
/* Assert START */
- status = twsi_start(adap, expected_start_status, flags);
+ status = twsi_start(adap, expected_start_status);
/* Send out the address if the start went well */
if (status == 0)
- status = twsi_send(adap, addr, expected_addr_status,
- flags);
+ status = twsi_send(adap, addr, expected_addr_status);
/* Return 0, or the status of the first failure */
return status;
}
@@ -404,14 +412,13 @@ static int i2c_begin(struct i2c_adapter *adap, int expected_start_status,
static int twsi_i2c_probe(struct i2c_adapter *adap, uchar chip)
{
u8 dummy_byte;
- u8 flags = 0;
int status;
/* Begin i2c read */
- status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1) | 1, &flags);
+ status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1) | 1);
/* Dummy read was accepted: receive byte, but NAK it. */
if (status == 0)
- status = twsi_recv(adap, &dummy_byte, &flags);
+ status = twsi_recv(adap, &dummy_byte, MVTWSI_READ_NAK);
/* Stop transaction */
twsi_stop(adap, 0);
/* Return 0, or the status of the first failure */
@@ -430,29 +437,23 @@ static int twsi_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
int alen, uchar *data, int length)
{
int status;
- u8 flags = 0;
/* Begin i2c write to send the address bytes */
- status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1), &flags);
+ status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1));
/* Send address bytes */
while ((status == 0) && alen--)
status = twsi_send(adap, addr >> (8*alen),
- MVTWSI_STATUS_DATA_W_ACK, &flags);
+ MVTWSI_STATUS_DATA_W_ACK);
/* Begin i2c read to receive data bytes */
if (status == 0)
status = i2c_begin(adap, MVTWSI_STATUS_REPEATED_START,
- (chip << 1) | 1, &flags);
- /* Prepare ACK if at least one byte must be received */
- if (length > 0)
- flags |= MVTWSI_CONTROL_ACK;
- /* Receive actual data bytes */
- while ((status == 0) && length--) {
- /* Set NAK if we if we have nothing more to read */
- if (length == 0)
- flags &= ~MVTWSI_CONTROL_ACK;
- /* Read current byte */
- status = twsi_recv(adap, data++, &flags);
- }
+ (chip << 1) | 1);
+ /* Receive actual data bytes; set NAK if we if we have nothing more to
+ * read */
+ while ((status == 0) && length--)
+ status = twsi_recv(adap, data++,
+ length > 0 ?
+ MVTWSI_READ_ACK : MVTWSI_READ_NAK);
/* Stop transaction */
status = twsi_stop(adap, status);
/* Return 0, or the status of the first failure */
@@ -466,19 +467,17 @@ static int twsi_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
int alen, uchar *data, int length)
{
int status;
- u8 flags = 0;
/* Begin i2c write to send first the address bytes, then the
* data bytes */
- status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1), &flags);
+ status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1));
/* Send address bytes */
while ((status == 0) && alen--)
status = twsi_send(adap, addr >> (8*alen),
- MVTWSI_STATUS_DATA_W_ACK, &flags);
+ MVTWSI_STATUS_DATA_W_ACK);
/* Send data bytes */
while ((status == 0) && (length-- > 0))
- status = twsi_send(adap, *(data++), MVTWSI_STATUS_DATA_W_ACK,
- &flags);
+ status = twsi_send(adap, *(data++), MVTWSI_STATUS_DATA_W_ACK);
/* Stop transaction */
status = twsi_stop(adap, status);
/* Return 0, or the status of the first failure */
generated by cgit v1.1 at 2024-12-13 23:08:07 +0000