* [PATCH v3 0/3] am335x: set pinmux registers from pins debug file
@ 2021-05-20 20:27 Dario Binacchi
2021-05-20 20:27 ` [PATCH v3 3/3] pinctrl: single: set pinmux " Dario Binacchi
2021-05-25 0:18 ` [PATCH v3 0/3] am335x: set pinmux registers " Linus Walleij
0 siblings, 2 replies; 4+ messages in thread
From: Dario Binacchi @ 2021-05-20 20:27 UTC (permalink / raw)
To: linux-kernel
Cc: Dario Binacchi, Tony Lindgren, Drew Fustini, Linus Walleij,
Andy Shevchenko, Haojian Zhuang, Jonathan Corbet,
linux-arm-kernel, linux-doc, linux-gpio, linux-omap
The patch was born from the need to change the slew rate of the LCD pins
of a custom AM335x board during EMC tests. The AM335x, as described in a
note in section 9.1 of its reference manual [1], is unable to write
pinmux registers from user space. The series now makes it possible to
write these registers from the pins debug file.
[1] https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf
Changes in v3:
- Use strncpy_from_user() instead of copy_from_user().
- Do not shadow the error code returned by kstrtouint().
- Change pin_dbg_set() interface (char *buf --> unsigned int val).
- Describe pin_dbg_set().
- Remove CONFIG_DEV_MEM dependency.
- Change pcs_pin_dbg_set() interface (char *buf -> unsigned int val).
Changes in v2:
- Remove CONFIG_SOC_AM33XX dependency.
Dario Binacchi (3):
docs/pinctrl: update `pins' description under debugfs
pinctrl: core: configure pinmux from pins debug file
pinctrl: single: set pinmux from pins debug file
Documentation/driver-api/pin-control.rst | 3 ++
drivers/pinctrl/core.c | 63 +++++++++++++++++++++++-
drivers/pinctrl/pinctrl-single.c | 13 +++++
include/linux/pinctrl/pinctrl.h | 4 ++
4 files changed, 81 insertions(+), 2 deletions(-)
--
2.17.1
^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v3 3/3] pinctrl: single: set pinmux from pins debug file
2021-05-20 20:27 [PATCH v3 0/3] am335x: set pinmux registers from pins debug file Dario Binacchi
@ 2021-05-20 20:27 ` Dario Binacchi
2021-05-21 6:44 ` Vladimir Zapolskiy
2021-05-25 0:18 ` [PATCH v3 0/3] am335x: set pinmux registers " Linus Walleij
1 sibling, 1 reply; 4+ messages in thread
From: Dario Binacchi @ 2021-05-20 20:27 UTC (permalink / raw)
To: linux-kernel
Cc: Dario Binacchi, Tony Lindgren, Drew Fustini, Linus Walleij,
Andy Shevchenko, Haojian Zhuang, linux-arm-kernel, linux-gpio,
linux-omap
As described in section 9.1 of the TI reference manual for AM335x [1],
"For writing to the control module registers, the MPU will need to be in
privileged mode of operation and writes will not work from user mode".
By adding the pin_dbg_set helper to pcs_pinctrl_ops it will be possible
to write these registers from the pins debug:
cd /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single/
echo <pin-number> <reg-value> >pins
[1] https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf
Signed-off-by: Dario Binacchi <dariobin@libero.it>
---
Changes in v3:
- Remove CONFIG_DEV_MEM dependency.
- Change pcs_pin_dbg_set() interface (char *buf -> unsigned int val).
Changes in v2:
- Remove CONFIG_SOC_AM33XX dependency.
drivers/pinctrl/pinctrl-single.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
index 2c9c9835f375..1b75236563cf 100644
--- a/drivers/pinctrl/pinctrl-single.c
+++ b/drivers/pinctrl/pinctrl-single.c
@@ -313,6 +313,18 @@ static void pcs_pin_dbg_show(struct pinctrl_dev *pctldev,
seq_printf(s, "%zx %08x %s ", pa, val, DRIVER_NAME);
}
+static int pcs_pin_dbg_set(struct pinctrl_dev *pctldev, unsigned int pin,
+ unsigned int val)
+{
+ struct pcs_device *pcs;
+ unsigned int mux_bytes;
+
+ pcs = pinctrl_dev_get_drvdata(pctldev);
+ mux_bytes = pcs->width / BITS_PER_BYTE;
+ pcs->write(val, pcs->base + pin * mux_bytes);
+ return 0;
+}
+
static void pcs_dt_free_map(struct pinctrl_dev *pctldev,
struct pinctrl_map *map, unsigned num_maps)
{
@@ -331,6 +343,7 @@ static const struct pinctrl_ops pcs_pinctrl_ops = {
.get_group_name = pinctrl_generic_get_group_name,
.get_group_pins = pinctrl_generic_get_group_pins,
.pin_dbg_show = pcs_pin_dbg_show,
+ .pin_dbg_set = pcs_pin_dbg_set,
.dt_node_to_map = pcs_dt_node_to_map,
.dt_free_map = pcs_dt_free_map,
};
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3 3/3] pinctrl: single: set pinmux from pins debug file
2021-05-20 20:27 ` [PATCH v3 3/3] pinctrl: single: set pinmux " Dario Binacchi
@ 2021-05-21 6:44 ` Vladimir Zapolskiy
0 siblings, 0 replies; 4+ messages in thread
From: Vladimir Zapolskiy @ 2021-05-21 6:44 UTC (permalink / raw)
To: Dario Binacchi, linux-kernel
Cc: Tony Lindgren, Drew Fustini, Linus Walleij, Andy Shevchenko,
Haojian Zhuang, linux-arm-kernel, linux-gpio, linux-omap
Hello Dario,
On 5/20/21 11:27 PM, Dario Binacchi wrote:
> As described in section 9.1 of the TI reference manual for AM335x [1],
> "For writing to the control module registers, the MPU will need to be in
> privileged mode of operation and writes will not work from user mode".
> By adding the pin_dbg_set helper to pcs_pinctrl_ops it will be possible
> to write these registers from the pins debug:
this makes little sense, because it should be possible to write to the
registers without introduction of this interface, pin group/function
is the right level of abstraction for your particular task.
> cd /sys/kernel/debug/pinctrl/44e10800.pinmux-pinctrl-single/
> echo <pin-number> <reg-value> >pins
>
> [1] https://www.ti.com/lit/ug/spruh73q/spruh73q.pdf
>
> Signed-off-by: Dario Binacchi <dariobin@libero.it>
I strongly object against this new interface to be added.
--
Best wishes,
Vladimir
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3 0/3] am335x: set pinmux registers from pins debug file
2021-05-20 20:27 [PATCH v3 0/3] am335x: set pinmux registers from pins debug file Dario Binacchi
2021-05-20 20:27 ` [PATCH v3 3/3] pinctrl: single: set pinmux " Dario Binacchi
@ 2021-05-25 0:18 ` Linus Walleij
1 sibling, 0 replies; 4+ messages in thread
From: Linus Walleij @ 2021-05-25 0:18 UTC (permalink / raw)
To: Dario Binacchi
Cc: linux-kernel, Tony Lindgren, Drew Fustini, Andy Shevchenko,
Haojian Zhuang, Jonathan Corbet, Linux ARM,
Linux Doc Mailing List, open list:GPIO SUBSYSTEM, Linux-OMAP
On Thu, May 20, 2021 at 10:27 PM Dario Binacchi <dariobin@libero.it> wrote:
> The patch was born from the need to change the slew rate of the LCD pins
> of a custom AM335x board during EMC tests. The AM335x, as described in a
> note in section 9.1 of its reference manual [1], is unable to write
> pinmux registers from user space. The series now makes it possible to
> write these registers from the pins debug file.
I am going to hold this series back pending more discussion on the ABI
and whether it is useful.
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-05-25 0:18 UTC | newest]
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2021-05-20 20:27 [PATCH v3 0/3] am335x: set pinmux registers from pins debug file Dario Binacchi
2021-05-20 20:27 ` [PATCH v3 3/3] pinctrl: single: set pinmux " Dario Binacchi
2021-05-21 6:44 ` Vladimir Zapolskiy
2021-05-25 0:18 ` [PATCH v3 0/3] am335x: set pinmux registers " Linus Walleij
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