diff mbox series

[v3,04/10] counter: stm32-timer-cnt: introduce clock signal

Message ID 20231220145726.640627-5-fabrice.gasnier@foss.st.com (mailing list archive)
State New, archived
Headers show
Series counter: Add stm32 timer events support | expand

Commit Message

Fabrice Gasnier Dec. 20, 2023, 2:57 p.m. UTC
Introduce the internal clock signal, used to count when in simple rising
function. Also add the "frequency" extension to the clock signal.

With this patch, signal action reports a consistent state when "increase"
function is used, and the counting frequency:
    $ echo increase > function
    $ grep -H "" signal*_action
    signal0_action:none
    signal1_action:none
    signal2_action:rising edge
    $ echo 1 > enable
    $ cat count
    25425
    $ cat count
    44439
    $ cat ../signal2/frequency
    208877930

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
---
Changes in v3:
- split the patch in 3 parts: signal definition becomes a pre-cursor patch,
  add the "prescaler" extension in its own patch.
- Move the clock signal at the end of the signals array, so existing
  userspace programs that may rely on signal0 being "Channel 1" for
  example will remain compatible.
---
 drivers/counter/stm32-timer-cnt.c | 53 ++++++++++++++++++++++++++++---
 1 file changed, 49 insertions(+), 4 deletions(-)

Comments

William Breathitt Gray Jan. 8, 2024, 4:46 p.m. UTC | #1
On Wed, Dec 20, 2023 at 03:57:20PM +0100, Fabrice Gasnier wrote:
> Introduce the internal clock signal, used to count when in simple rising
> function. Also add the "frequency" extension to the clock signal.
> 
> With this patch, signal action reports a consistent state when "increase"
> function is used, and the counting frequency:
>     $ echo increase > function
>     $ grep -H "" signal*_action
>     signal0_action:none
>     signal1_action:none
>     signal2_action:rising edge
>     $ echo 1 > enable
>     $ cat count
>     25425
>     $ cat count
>     44439
>     $ cat ../signal2/frequency
>     208877930
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>

Reviewed-by: William Breathitt Gray <william.gray@linaro.org>

The code is all right, but some minor suggestions below.

> +static struct counter_comp stm32_count_clock_ext[] = {
> +	COUNTER_COMP_SIGNAL_U64("frequency", stm32_count_clk_get_freq, NULL),

It might be worth introducing a new COUNTER_COMP_FREQUENCY() macro now
that we have a second driver with the 'frequency' extension
(ti-ecap-capture also has 'frequency'). But it's up to you if you want
to add a precursor patch to this series, or I'll introduce it separately
myself in a independent patch.

> @@ -287,7 +321,13 @@ static struct counter_signal stm32_signals[] = {
>  	{
>  		.id = STM32_CH2_SIG,
>  		.name = "Channel 2"
> -	}
> +	},
> +	{
> +		.id = STM32_CLOCK_SIG,
> +		.name = "Clock Signal",

The word "Signal" feels unnecessary to me when both the sysfs path and
data structure will have 'signal' already. Do you think "Clock" by
itself is clear enough?

William Breathitt Gray
Fabrice Gasnier Feb. 27, 2024, 5:43 p.m. UTC | #2
On 1/8/24 17:46, William Breathitt Gray wrote:
> On Wed, Dec 20, 2023 at 03:57:20PM +0100, Fabrice Gasnier wrote:
>> Introduce the internal clock signal, used to count when in simple rising
>> function. Also add the "frequency" extension to the clock signal.
>>
>> With this patch, signal action reports a consistent state when "increase"
>> function is used, and the counting frequency:
>>     $ echo increase > function
>>     $ grep -H "" signal*_action
>>     signal0_action:none
>>     signal1_action:none
>>     signal2_action:rising edge
>>     $ echo 1 > enable
>>     $ cat count
>>     25425
>>     $ cat count
>>     44439
>>     $ cat ../signal2/frequency
>>     208877930
>>
>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
> 
> Reviewed-by: William Breathitt Gray <william.gray@linaro.org>
> 
> The code is all right, but some minor suggestions below.
> 
>> +static struct counter_comp stm32_count_clock_ext[] = {
>> +	COUNTER_COMP_SIGNAL_U64("frequency", stm32_count_clk_get_freq, NULL),
> 
> It might be worth introducing a new COUNTER_COMP_FREQUENCY() macro now
> that we have a second driver with the 'frequency' extension
> (ti-ecap-capture also has 'frequency'). But it's up to you if you want
> to add a precursor patch to this series, or I'll introduce it separately
> myself in a independent patch.

Thanks for suggesting.

I added a precursor patch to this series.
I guess you wishes to see it used in both ti-ecap-capture and
stm32-timer-cnt. I only cared about stm32-timer-cnt in this series.

Can I let you do ti-ecap-capture change if/when you're going to apply it?

> 
>> @@ -287,7 +321,13 @@ static struct counter_signal stm32_signals[] = {
>>  	{
>>  		.id = STM32_CH2_SIG,
>>  		.name = "Channel 2"
>> -	}
>> +	},
>> +	{
>> +		.id = STM32_CLOCK_SIG,
>> +		.name = "Clock Signal",
> 
> The word "Signal" feels unnecessary to me when both the sysfs path and
> data structure will have 'signal' already. Do you think "Clock" by
> itself is clear enough?

Agreed, I updated in v4.

Best Regards,
Fabrice

> 
> William Breathitt Gray
William Breathitt Gray Feb. 29, 2024, 6:58 p.m. UTC | #3
On Tue, Feb 27, 2024 at 06:43:20PM +0100, Fabrice Gasnier wrote:
> On 1/8/24 17:46, William Breathitt Gray wrote:
> > On Wed, Dec 20, 2023 at 03:57:20PM +0100, Fabrice Gasnier wrote:
> >> Introduce the internal clock signal, used to count when in simple rising
> >> function. Also add the "frequency" extension to the clock signal.
> >>
> >> With this patch, signal action reports a consistent state when "increase"
> >> function is used, and the counting frequency:
> >>     $ echo increase > function
> >>     $ grep -H "" signal*_action
> >>     signal0_action:none
> >>     signal1_action:none
> >>     signal2_action:rising edge
> >>     $ echo 1 > enable
> >>     $ cat count
> >>     25425
> >>     $ cat count
> >>     44439
> >>     $ cat ../signal2/frequency
> >>     208877930
> >>
> >> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@foss.st.com>
> > 
> > Reviewed-by: William Breathitt Gray <william.gray@linaro.org>
> > 
> > The code is all right, but some minor suggestions below.
> > 
> >> +static struct counter_comp stm32_count_clock_ext[] = {
> >> +	COUNTER_COMP_SIGNAL_U64("frequency", stm32_count_clk_get_freq, NULL),
> > 
> > It might be worth introducing a new COUNTER_COMP_FREQUENCY() macro now
> > that we have a second driver with the 'frequency' extension
> > (ti-ecap-capture also has 'frequency'). But it's up to you if you want
> > to add a precursor patch to this series, or I'll introduce it separately
> > myself in a independent patch.
> 
> Thanks for suggesting.
> 
> I added a precursor patch to this series.
> I guess you wishes to see it used in both ti-ecap-capture and
> stm32-timer-cnt. I only cared about stm32-timer-cnt in this series.
> 
> Can I let you do ti-ecap-capture change if/when you're going to apply it?

Thanks Fabrice, I'll pick up the precursor patch so we an start using it
in other drivers. Syed will take on the ti-ecap-capture change, and I've
CC'd Vignesh and Julien to this email as well so they are aware of the
incoming patch.

William Breathitt Gray
diff mbox series

Patch

diff --git a/drivers/counter/stm32-timer-cnt.c b/drivers/counter/stm32-timer-cnt.c
index c34747d7857e..21a9c20c4281 100644
--- a/drivers/counter/stm32-timer-cnt.c
+++ b/drivers/counter/stm32-timer-cnt.c
@@ -23,6 +23,7 @@ 
 
 #define STM32_CH1_SIG		0
 #define STM32_CH2_SIG		1
+#define STM32_CLOCK_SIG		2
 
 struct stm32_timer_regs {
 	u32 cr1;
@@ -226,6 +227,10 @@  static struct counter_comp stm32_count_ext[] = {
 			     stm32_count_ceiling_write),
 };
 
+static const enum counter_synapse_action stm32_clock_synapse_actions[] = {
+	COUNTER_SYNAPSE_ACTION_RISING_EDGE,
+};
+
 static const enum counter_synapse_action stm32_synapse_actions[] = {
 	COUNTER_SYNAPSE_ACTION_NONE,
 	COUNTER_SYNAPSE_ACTION_BOTH_EDGES
@@ -246,7 +251,10 @@  static int stm32_action_read(struct counter_device *counter,
 	switch (function) {
 	case COUNTER_FUNCTION_INCREASE:
 		/* counts on internal clock when CEN=1 */
-		*action = COUNTER_SYNAPSE_ACTION_NONE;
+		if (synapse->signal->id == STM32_CLOCK_SIG)
+			*action = COUNTER_SYNAPSE_ACTION_RISING_EDGE;
+		else
+			*action = COUNTER_SYNAPSE_ACTION_NONE;
 		return 0;
 	case COUNTER_FUNCTION_QUADRATURE_X2_A:
 		/* counts up/down on TI1FP1 edge depending on TI2FP2 level */
@@ -264,7 +272,10 @@  static int stm32_action_read(struct counter_device *counter,
 		return 0;
 	case COUNTER_FUNCTION_QUADRATURE_X4:
 		/* counts up/down on both TI1FP1 and TI2FP2 edges */
-		*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
+		if (synapse->signal->id == STM32_CH1_SIG || synapse->signal->id == STM32_CH2_SIG)
+			*action = COUNTER_SYNAPSE_ACTION_BOTH_EDGES;
+		else
+			*action = COUNTER_SYNAPSE_ACTION_NONE;
 		return 0;
 	default:
 		return -EINVAL;
@@ -279,7 +290,30 @@  static const struct counter_ops stm32_timer_cnt_ops = {
 	.action_read = stm32_action_read,
 };
 
+static int stm32_count_clk_get_freq(struct counter_device *counter,
+				    struct counter_signal *signal, u64 *freq)
+{
+	struct stm32_timer_cnt *const priv = counter_priv(counter);
+
+	*freq = clk_get_rate(priv->clk);
+
+	return 0;
+}
+
+static struct counter_comp stm32_count_clock_ext[] = {
+	COUNTER_COMP_SIGNAL_U64("frequency", stm32_count_clk_get_freq, NULL),
+};
+
 static struct counter_signal stm32_signals[] = {
+	/*
+	 * Need to declare all the signals as a static array, and keep the signals order here,
+	 * even if they're unused or unexisting on some timer instances. It's an abstraction,
+	 * e.g. high level view of the counter features.
+	 *
+	 * Userspace programs may rely on signal0 to be "Channel 1", signal1 to be "Channel 2",
+	 * and so on. When a signal is unexisting, the COUNTER_SYNAPSE_ACTION_NONE can be used,
+	 * to indicate that a signal doesn't affect the counter.
+	 */
 	{
 		.id = STM32_CH1_SIG,
 		.name = "Channel 1"
@@ -287,7 +321,13 @@  static struct counter_signal stm32_signals[] = {
 	{
 		.id = STM32_CH2_SIG,
 		.name = "Channel 2"
-	}
+	},
+	{
+		.id = STM32_CLOCK_SIG,
+		.name = "Clock Signal",
+		.ext = stm32_count_clock_ext,
+		.num_ext = ARRAY_SIZE(stm32_count_clock_ext),
+	},
 };
 
 static struct counter_synapse stm32_count_synapses[] = {
@@ -300,7 +340,12 @@  static struct counter_synapse stm32_count_synapses[] = {
 		.actions_list = stm32_synapse_actions,
 		.num_actions = ARRAY_SIZE(stm32_synapse_actions),
 		.signal = &stm32_signals[STM32_CH2_SIG]
-	}
+	},
+	{
+		.actions_list = stm32_clock_synapse_actions,
+		.num_actions = ARRAY_SIZE(stm32_clock_synapse_actions),
+		.signal = &stm32_signals[STM32_CLOCK_SIG]
+	},
 };
 
 static struct counter_count stm32_counts = {