When attempting to use GPIO via the sm501 unit on the TQM5200 board,
GPIO operations would only function if during the same boot u-boot's
"fkt led" command had initialized the sm501. Comparing the sm501's
registers with and without running the "fkt led" command turned up one
significant difference: u-boot had enabled the GPIO power gate.
Changing the Linux sm501 driver to enable the GPIO power gate allows
GPIO to work without first initializing it with u-boot.
Signed-off-by: Josh Triplett <j...@joshtriplett.org>
---
drivers/mfd/sm501.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)
diff --git a/drivers/mfd/sm501.c b/drivers/mfd/sm501.c
index df3702c..d7a0ab9 100644
--- a/drivers/mfd/sm501.c
+++ b/drivers/mfd/sm501.c
@@ -1089,6 +1089,7 @@ static int __devinit sm501_register_gpio(struct
sm501_devdata *sm)
goto err_low_chip;
}
+ sm501_unit_power(sm->dev, SM501_GATE_GPIO, 1);
gpio->registered = 1;
return 0;
@@ -1118,6 +1119,8 @@ static void sm501_gpio_remove(struct sm501_devdata *sm)
if (!sm->gpio.registered)
return;
+ sm501_unit_power(sm->dev, SM501_GATE_GPIO, 0);
+
ret = gpiochip_remove(&gpio->low.gpio);
if (ret)
dev_err(sm->dev, "cannot remove low chip, cannot tidy up\n");
--
1.7.5.4
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