The i2c-pnx driver implements the i2c specification incorrectly. The
specification allows for 'repeated start' transactions in which the i2c
master generates two start conditions without generating a stop condition in
between them. However, the i2c-pnx driver always generates a stop condition
after every start condition. This patch correctly implements repeated start
transactions.
---
drivers/i2c/busses/i2c-pnx.c | 88 ++++++++++++++++++++++++++++++++++----------
include/linux/i2c-pnx.h | 2 +
2 files changed, 71 insertions(+), 19 deletions(-)
diff --git a/drivers/i2c/busses/i2c-pnx.c b/drivers/i2c/busses/i2c-pnx.c
index e814a36..7bac253 100644
--- a/drivers/i2c/busses/i2c-pnx.c
+++ b/drivers/i2c/busses/i2c-pnx.c
@@ -139,20 +139,24 @@ static int i2c_pnx_start(unsigned char slave_addr,
}
/* First, make sure bus is idle */
- if (wait_timeout(alg_data)) {
- /* Somebody else is monopolizing the bus */
- dev_err(&alg_data->adapter.dev,
- "%s: Bus busy. Slave addr = %02x, cntrl = %x, stat = %x\n",
- alg_data->adapter.name, slave_addr,
- ioread32(I2C_REG_CTL(alg_data)),
- ioread32(I2C_REG_STS(alg_data)));
- return -EBUSY;
- } else if (ioread32(I2C_REG_STS(alg_data)) & mstatus_afi) {
- /* Sorry, we lost the bus */
- dev_err(&alg_data->adapter.dev,
- "%s: Arbitration failure. Slave addr = %02x\n",
- alg_data->adapter.name, slave_addr);
- return -EIO;
+ if (!alg_data->write_start_read) {
+ if (wait_timeout(alg_data)) {
+ /* Somebody else is monopolizing the bus */
+ dev_err(&alg_data->adapter.dev,
+ "%s: Bus busy. Slave addr = %02x, cntrl = %x, stat = %x\n",
+ alg_data->adapter.name, slave_addr,
+ ioread32(I2C_REG_CTL(alg_data)),
+ ioread32(I2C_REG_STS(alg_data)));
+ return -EBUSY;
+ } else if (ioread32(I2C_REG_STS(alg_data)) & mstatus_afi) {
+ /* Sorry, we lost the bus */
+ dev_err(&alg_data->adapter.dev,
+ "%s: Arbitration failure. Slave addr = %02x\n",
+ alg_data->adapter.name, slave_addr);
+ return -EIO;
+ }
+ } else {
+ alg_data->write_start_read = 0;
}
/*
@@ -168,6 +172,9 @@ static int i2c_pnx_start(unsigned char slave_addr,
/* Write the slave address, START bit and R/W bit */
iowrite32((slave_addr << 1) | start_bit | alg_data->mif.mode,
I2C_REG_TX(alg_data));
+ iowrite32(ioread32(I2C_REG_CTL(alg_data)) | mcntrl_afie | mcntrl_naie |
+ (alg_data->write_start_read ? 0 : mcntrl_drmie),
+ I2C_REG_CTL(alg_data));
dev_dbg(&alg_data->adapter.dev, "%s(): exit\n", __func__);
@@ -220,8 +227,14 @@ static int i2c_pnx_master_xmit(struct i2c_pnx_algo_data *alg_data)
/* We still have something to talk about... */
val = *alg_data->mif.buf++;
- if (alg_data->mif.len == 1)
+ if (alg_data->mif.len == 1 && !(alg_data->repeated_start)) {
+ alg_data->write_start_read = 0;
val |= stop_bit;
+ } else if (alg_data->mif.len == 1) {
+ alg_data->write_start_read = 1;
+ } else {
+ alg_data->write_start_read = 0;
+ }
alg_data->mif.len--;
iowrite32(val, I2C_REG_TX(alg_data));
@@ -281,7 +294,7 @@ static int i2c_pnx_master_xmit(struct i2c_pnx_algo_data *alg_data)
*/
static int i2c_pnx_master_rcv(struct i2c_pnx_algo_data *alg_data)
{
- unsigned int val = 0;
+ unsigned int val = 0xFF;
u32 ctl = 0;
dev_dbg(&alg_data->adapter.dev, "%s(): entering: stat = %04x.\n",
@@ -467,6 +480,11 @@ static inline void bus_reset_if_active(struct i2c_pnx_algo_data *alg_data)
alg_data->adapter.name);
iowrite32(ioread32(I2C_REG_CTL(alg_data)) | mcntrl_reset,
I2C_REG_CTL(alg_data));
+
+ dev_dbg(&alg_data->adapter.dev,
+ "%s: Resetting bus\n", __func__);
+ iowrite32(0xff | start_bit, I2C_REG_TX(alg_data));
+
wait_reset(alg_data);
} else if (!(stat & mstatus_rfe) || !(stat & mstatus_tfe)) {
/* If there is data in the fifo's after transfer,
@@ -482,6 +500,32 @@ static inline void bus_reset_if_active(struct i2c_pnx_algo_data *alg_data)
}
}
+static inline void
+setup_repeated_start(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) {
+ struct i2c_pnx_algo_data *alg_data = adap->algo_data;
+
+ if (1 < num && !(msgs[0].flags) && ((msgs[1].flags) & I2C_M_RD)) {
+ alg_data->repeated_start = 1;
+ dev_dbg(&adap->dev,
+ "%s(): repeated start\n", __func__);
+ } else if (1 < num) {
+ alg_data->repeated_start = 0;
+ dev_dbg(&adap->dev,
+ "%s(): non-repeated start\n", __func__);
+ } else if (1 < msgs[0].len) {
+ alg_data->repeated_start = 0;
+ if (!msgs[0].flags) {
+ dev_dbg(&adap->dev,
+ "%s(): multi-byte write\n", __func__);
+ } else {
+ dev_dbg(&adap->dev,
+ "%s(): multi-byte read\n", __func__);
+ }
+ } else {
+ alg_data->repeated_start = 0;
+ }
+}
+
/**
* i2c_pnx_xfer - generic transfer entry point
* @adap: pointer to I2C adapter structure
@@ -504,6 +548,9 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
bus_reset_if_active(alg_data);
+ setup_repeated_start(adap, msgs, num);
+ alg_data->write_start_read = 0;
+
/* Process transactions in a loop. */
for (i = 0; rc >= 0 && i < num; i++) {
u8 addr;
@@ -527,8 +574,10 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
alg_data->mif.ret = 0;
alg_data->last = (i == num - 1);
- dev_dbg(&alg_data->adapter.dev, "%s(): mode %d, %d bytes\n",
- __func__, alg_data->mif.mode, alg_data->mif.len);
+ dev_dbg(&alg_data->adapter.dev, "%s(): mode %s, %d bytes\n",
+ __func__,
+ (alg_data->mif.mode == I2C_SMBUS_READ ? "R" : "W"),
+ alg_data->mif.len);
i2c_pnx_arm_timer(alg_data);
@@ -537,7 +586,8 @@ i2c_pnx_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
/* Enable master interrupt */
iowrite32(ioread32(I2C_REG_CTL(alg_data)) | mcntrl_afie |
- mcntrl_naie | mcntrl_drmie,
+ mcntrl_naie |
+ (alg_data->write_start_read ? 0 : mcntrl_drmie),
I2C_REG_CTL(alg_data));
/* Put start-code and slave-address on the bus. */
diff --git a/include/linux/i2c-pnx.h b/include/linux/i2c-pnx.h
index 5388326..1c5fa84 100644
--- a/include/linux/i2c-pnx.h
+++ b/include/linux/i2c-pnx.h
@@ -29,6 +29,8 @@ struct i2c_pnx_algo_data {
void __iomem *ioaddr;
struct i2c_pnx_mif mif;
int last;
+ int repeated_start;
+ int write_start_read;
struct clk *clk;
struct i2c_adapter adapter;
int irq;
--
2.4.5
--
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