aboutsummaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
authorGregory Bean <gbean@codeaurora.org>2010-09-09 16:38:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-09-09 18:57:24 -0700
commit5affb607720d734ca572b8a77c5c7d62d3042b6f (patch)
tree5c3a675bef03570958fc4e9baffb318ec7f64e31
parent0dcc48c15f63ee86c2fcd33968b08d651f0360a5 (diff)
downloadmrst-s0i3-test-5affb607720d734ca572b8a77c5c7d62d3042b6f.tar.gz
mrst-s0i3-test-5affb607720d734ca572b8a77c5c7d62d3042b6f.tar.xz
mrst-s0i3-test-5affb607720d734ca572b8a77c5c7d62d3042b6f.zip
gpio: sx150x: correct and refine reset-on-probe behavior
Replace the arbitrary software-reset call from the device-probe method, because: - It is defective. To work correctly, it should be two byte writes, not a single word write. As it stands, it does nothing. - Some devices with sx150x expanders installed have their NRESET pins ganged on the same line, so resetting one causes the others to reset - not a nice thing to do arbitrarily! - The probe, usually taking place at boot, implies a recent hard-reset, so a software reset at this point is just a waste of energy anyway. Therefore, make it optional, defaulting to off, as this will match the common case of probing at powerup and also matches the current broken no-op behavior. Signed-off-by: Gregory Bean <gbean@codeaurora.org> Reviewed-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/gpio/sx150x.c26
-rw-r--r--include/linux/i2c/sx150x.h4
2 files changed, 25 insertions, 5 deletions
diff --git a/drivers/gpio/sx150x.c b/drivers/gpio/sx150x.c
index b42f42ca70c..823559ab0e2 100644
--- a/drivers/gpio/sx150x.c
+++ b/drivers/gpio/sx150x.c
@@ -459,17 +459,33 @@ static int sx150x_init_io(struct sx150x_chip *chip, u8 base, u16 cfg)
return err;
}
-static int sx150x_init_hw(struct sx150x_chip *chip,
- struct sx150x_platform_data *pdata)
+static int sx150x_reset(struct sx150x_chip *chip)
{
- int err = 0;
+ int err;
- err = i2c_smbus_write_word_data(chip->client,
+ err = i2c_smbus_write_byte_data(chip->client,
chip->dev_cfg->reg_reset,
- 0x3412);
+ 0x12);
if (err < 0)
return err;
+ err = i2c_smbus_write_byte_data(chip->client,
+ chip->dev_cfg->reg_reset,
+ 0x34);
+ return err;
+}
+
+static int sx150x_init_hw(struct sx150x_chip *chip,
+ struct sx150x_platform_data *pdata)
+{
+ int err = 0;
+
+ if (pdata->reset_during_probe) {
+ err = sx150x_reset(chip);
+ if (err < 0)
+ return err;
+ }
+
err = sx150x_i2c_write(chip->client,
chip->dev_cfg->reg_misc,
0x01);
diff --git a/include/linux/i2c/sx150x.h b/include/linux/i2c/sx150x.h
index ee3049cb9ba..52baa79d69a 100644
--- a/include/linux/i2c/sx150x.h
+++ b/include/linux/i2c/sx150x.h
@@ -63,6 +63,9 @@
* IRQ lines will appear. Similarly to gpio_base, the expander
* will create a block of irqs beginning at this number.
* This value is ignored if irq_summary is < 0.
+ * @reset_during_probe: If set to true, the driver will trigger a full
+ * reset of the chip at the beginning of the probe
+ * in order to place it in a known state.
*/
struct sx150x_platform_data {
unsigned gpio_base;
@@ -73,6 +76,7 @@ struct sx150x_platform_data {
u16 io_polarity;
int irq_summary;
unsigned irq_base;
+ bool reset_during_probe;
};
#endif /* __LINUX_I2C_SX150X_H */