[U-Boot] [PATCH] fsl_i2c: Add write-then-read transaction interface for I2C slave
Shaveta Leekha
shaveta at freescale.com
Mon Mar 3 09:58:38 CET 2014
Most of the I2C slaves support accesses in the typical style
viz.read/write series of bytes at particular address offset.
These transactions are currently supportd in the
i2c driver using i2c_read and i2c_write APIs. I2C EEPROMs,
RTC, etc fall in this category.
The transactions look like:"
START:Address:Tx:Offset:RESTART:Address[0..4]:Tx/Rx:data[0..n]:STOP"
However there are certain devices which support accesses in
terms of the transactions as follows:
"START:Address:Tx:Txdata[0..n1]:Clock_stretching:
RESTART:Address:Rx:data[0..n2]"
The Txdata is typically a command and some associated data,
similarly Rxdata could be command status plus some data received
as a response to the command sent.
i2c_write_read() function provides support for such transactions
(multiple bytes write followed by read)
Signed-off-by: Poonam Aggrwal <poonam.aggrwal at freescale.com>
Signed-off-by: Shaveta Leekha <shaveta at freescale.com>
---
drivers/i2c/fsl_i2c.c | 64 ++++++++++++++++++++++++++++++++++++++++++-----
drivers/i2c/i2c_core.c | 7 +++++
include/i2c.h | 19 ++++++++++---
3 files changed, 78 insertions(+), 12 deletions(-)
diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c
index 291ad94..838c1b1 100644
--- a/drivers/i2c/fsl_i2c.c
+++ b/drivers/i2c/fsl_i2c.c
@@ -472,6 +472,56 @@ fsl_i2c_write(struct i2c_adapter *adap, u8 dev, uint addr, int alen,
return -1;
}
+/* To perform any generic transaction on a I2C slave which involves
+
+ START: Address: Write bytes(cmd + data): clock extension:
+ RESTART: Address: Read bytes (data + status): STOP
+
+ This is different from standard I2C devices which are supported
+ in existing i2c_read and i2c_write functions.
+ */
+int
+fsl_i2c_write_read(struct i2c_adapter *adap, u8 dev, u8 *wdata, int wlength,
+ u8 *rdata, int rlength)
+{
+ struct fsl_i2c *device = (struct fsl_i2c *)i2c_dev[adap->hwadapnr];
+
+ int i = -1; /* signal error */
+
+ if (i2c_wait4bus(adap))
+ return -1;
+
+/* Generate a START and send the Address and the Tx Bytes to the slave.
+ * "START: Address: Write bytes wdata[wlength]"
+ */
+ if (i2c_write_addr(adap, dev, I2C_WRITE_BIT, 0) != 0)
+ i = __i2c_write(adap, wdata, wlength);
+
+ if (i != wlength)
+ return -1;
+
+/* Now issue a READ by generating a RESTART condition
+ * "RESTART: Address: Read bytes rdata[rlength]"
+ * Some slaves may also do clock stretching and keep the SCL low until
+ * they finish some command processing at their end. The I2C controller
+ * will wait for the clock stretching period to get over before generating
+ * the RESTART condition on the bus.
+ */
+ if (rlength
+ && i2c_write_addr(adap, dev, I2C_READ_BIT, 1) != 0)
+ i = __i2c_read(adap, rdata, rlength);
+
+/* Generate STOP */
+ writeb(I2C_CR_MEN, &device->cr);
+
+ if (i2c_wait4bus(adap)) /* Wait until STOP */
+ debug("i2c_write_read: wait4bus timed out\n");
+
+ if (i != rlength)
+ return -1;
+
+ return 0;
+}
static int
fsl_i2c_probe(struct i2c_adapter *adap, uchar chip)
@@ -503,12 +553,12 @@ static unsigned int fsl_i2c_set_bus_speed(struct i2c_adapter *adap,
* Register fsl i2c adapters
*/
U_BOOT_I2C_ADAP_COMPLETE(fsl_0, fsl_i2c_init, fsl_i2c_probe, fsl_i2c_read,
- fsl_i2c_write, fsl_i2c_set_bus_speed,
- CONFIG_SYS_FSL_I2C_SPEED, CONFIG_SYS_FSL_I2C_SLAVE,
- 0)
-#ifdef CONFIG_SYS_FSL_I2C2_OFFSET
+ fsl_i2c_write, fsl_i2c_write_read,
+ fsl_i2c_set_bus_speed, CONFIG_SYS_FSL_I2C_SPEED,
+ CONFIG_SYS_FSL_I2C_SLAVE, 0);
+#ifdef CONFIG_SYS_I2C2_OFFSET
U_BOOT_I2C_ADAP_COMPLETE(fsl_1, fsl_i2c_init, fsl_i2c_probe, fsl_i2c_read,
- fsl_i2c_write, fsl_i2c_set_bus_speed,
- CONFIG_SYS_FSL_I2C2_SPEED, CONFIG_SYS_FSL_I2C2_SLAVE,
- 1)
+ fsl_i2c_write, fsl_i2c_write_read,
+ fsl_i2c_set_bus_speed, CONFIG_SYS_FSL_I2C2_SPEED,
+ CONFIG_SYS_FSL_I2C2_SLAVE, 1);
#endif
diff --git a/drivers/i2c/i2c_core.c b/drivers/i2c/i2c_core.c
index 18d6736..6647856 100644
--- a/drivers/i2c/i2c_core.c
+++ b/drivers/i2c/i2c_core.c
@@ -341,6 +341,13 @@ int i2c_write(uint8_t chip, unsigned int addr, int alen,
return I2C_ADAP->write(I2C_ADAP, chip, addr, alen, buffer, len);
}
+int i2c_write_read(uchar chip, uint8_t *wbuffer, int wlen, uint8_t *rbuffer,
+ int rlen)
+{
+ return I2C_ADAP->write_read(I2C_ADAP, chip, wbuffer, wlen,
+ rbuffer, rlen);
+}
+
unsigned int i2c_set_bus_speed(unsigned int speed)
{
unsigned int ret;
diff --git a/include/i2c.h b/include/i2c.h
index 1b4078e..7bac20a 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -65,6 +65,9 @@ struct i2c_adapter {
int (*write)(struct i2c_adapter *adap, uint8_t chip,
uint addr, int alen, uint8_t *buffer,
int len);
+ int (*write_read)(struct i2c_adapter *adap, uint8_t chip,
+ uint8_t *wbuffer, int wlength, uint8_t *rbuffer,
+ int rlength);
uint (*set_bus_speed)(struct i2c_adapter *adap,
uint speed);
int speed;
@@ -75,13 +78,14 @@ struct i2c_adapter {
char *name;
};
-#define U_BOOT_I2C_MKENT_COMPLETE(_init, _probe, _read, _write, \
+#define U_BOOT_I2C_MKENT_COMPLETE(_init, _probe, _read, _write, _write_read, \
_set_speed, _speed, _slaveaddr, _hwadapnr, _name) \
{ \
.init = _init, \
.probe = _probe, \
.read = _read, \
.write = _write, \
+ .write_read = _write_read, \
.set_bus_speed = _set_speed, \
.speed = _speed, \
.slaveaddr = _slaveaddr, \
@@ -90,10 +94,11 @@ struct i2c_adapter {
.name = #_name \
};
-#define U_BOOT_I2C_ADAP_COMPLETE(_name, _init, _probe, _read, _write, \
- _set_speed, _speed, _slaveaddr, _hwadapnr) \
- ll_entry_declare(struct i2c_adapter, _name, i2c) = \
- U_BOOT_I2C_MKENT_COMPLETE(_init, _probe, _read, _write, \
+#define U_BOOT_I2C_ADAP_COMPLETE(_name, _init, _probe, _read, _write, \
+ _write_read, _set_speed, _speed, _slaveaddr, \
+ _hwadapnr) \
+ ll_entry_declare(struct i2c_adapter, _name, i2c) = \
+ U_BOOT_I2C_MKENT_COMPLETE(_init, _probe, _read, _write, _write_read, \
_set_speed, _speed, _slaveaddr, _hwadapnr, _name);
struct i2c_adapter *i2c_get_adapter(int index);
@@ -237,6 +242,8 @@ int i2c_read(uint8_t chip, unsigned int addr, int alen,
int i2c_write(uint8_t chip, unsigned int addr, int alen,
uint8_t *buffer, int len);
+int i2c_write_read(uint8_t chip, uchar *wbuffer, int wlen, uchar *rbuffer,
+ int rlen);
/*
* Utility routines to read/write registers.
@@ -302,6 +309,8 @@ int i2c_probe(uchar chip);
*/
int i2c_read(uchar chip, uint addr, int alen, uchar *buffer, int len);
int i2c_write(uchar chip, uint addr, int alen, uchar *buffer, int len);
+int i2c_write_read(uchar chip, uchar *wbuffer, int wlen, uchar *rbuffer,
+ int rlen);
/*
* Utility routines to read/write registers.
--
1.7.6.GIT
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