Re: [STLinux Kernel] [PATCH 2/6] pinctrl: st: Introduce a 'get pin function' call

From: Maxime Coquelin
Date: Wed Mar 18 2015 - 13:00:41 EST

On 03/18/2015 05:51 PM, Lee Jones wrote:
On Wed, 18 Mar 2015, Maxime Coquelin wrote:

On 03/18/2015 11:51 AM, Lee Jones wrote:
This call fetches the numerical function value a specified pin is
currently operating in. Function zero is more often than not the
GPIO function. Greater than zero values represent an alternative
function. You'd need to either look those up in the Device Tree
sources or the Programmer's Manual.

Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx>
drivers/pinctrl/pinctrl-st.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/drivers/pinctrl/pinctrl-st.c b/drivers/pinctrl/pinctrl-st.c
index 9e5ec00..5362e45 100644
--- a/drivers/pinctrl/pinctrl-st.c
+++ b/drivers/pinctrl/pinctrl-st.c
@@ -460,6 +460,20 @@ static void st_pctl_set_function(struct st_pio_control *pc,
regmap_field_write(alt, val);
+static unsigned int st_pctl_get_pin_function(struct st_pio_control *pc, int pin)
+ struct regmap_field *alt = pc->alt;
+ unsigned int val;
+ int offset = pin * 4;
+ if (!alt)
+ return 0;
Shouldn't we print something if alt is NULL?
Else we can think we are on alternate 0.
That is the assumption that I've made. Is there isn't an alt, then a
pin can only be on Alt-0. Have I made the incorrect assumption here?
Just re-checked the code, and yes you are right.
No alt here means alt field of struct st_pctl_data is -1, which in turn means the register is not available.

You can forget my remark, and add my:
Acked-by: Maxime Coquelin <maxime.coquelin@xxxxxx>

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