Re: [PATCH v7 2/8] power: add power sequence library

[Peter Chen]

On Thu, Oct 13, 2016 at 09:04:42AM +0200, Heiko Stuebner wrote:
> > > > +static int __init pwrseq_generic_register(void)
> > > > +{
> > > > +   struct pwrseq_generic *pwrseq_gen;
> > > > +   int i;
> > > > +
> > > > +   for (i = 0; i < CONFIG_PWRSEQ_GENERIC_INSTANCE_NUMBER; i++) {
> > > > +   pwrseq_gen = kzalloc(sizeof(*pwrseq_gen), GFP_KERNEL);
> > > > +   if (!pwrseq_gen)
> > > > +   return -ENOMEM;
> > > > +
> > > > +   pwrseq_gen->pwrseq.pwrseq_of_match_table = 
> > > > generic_id_table;
> > > > +   pwrseq_gen->pwrseq.get = pwrseq_generic_get;
> > > > +   pwrseq_gen->pwrseq.on = pwrseq_generic_on;
> > > > +   pwrseq_gen->pwrseq.off = pwrseq_generic_off;
> > > > +   pwrseq_gen->pwrseq.put = pwrseq_generic_put;
> > > > +   pwrseq_gen->pwrseq.free = pwrseq_generic_free;
> > > > +
> > > > +   pwrseq_register(_gen->pwrseq);
> > > > +   }
> > > > +
> > > > +   return 0;
> > > > +}
> > > > +postcore_initcall(pwrseq_generic_register)
> > > 
> > > I see that you need to have it preallocated for the compatible matching,
> > > but wouldn't it also work to either just register the type and allocate
> > > dynamically or otherwise just allocate a new spare everytime
> > > pwrseq_generic_get() picks up the previous spare?
> > 
> > Before compatible matching, the host driver doesn't know which pwrseq type
> > for its child node, then doesn't know which pwrseq instance needs to be
> > allocated. From dts, we don't know which pwrseq type for the node.
> 
> yes, that is why I was suggesting allocating one (or two) here in 
> pwrseq_generic_register() and every time pwrseq_generic_get() grabs the last 
> free sequence instance, you allocate a new free spare one in that function.

Good idea.

-- 

Best Regards,
Peter Chen
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Re: [PATCH v7 2/8] power: add power sequence library

[Heiko Stuebner]

Am Donnerstag, 13. Oktober 2016, 09:22:16 CEST schrieb Peter Chen:
> On Wed, Oct 12, 2016 at 12:30:29PM +0200, Heiko Stuebner wrote:
> > Hi,
> > 
> > Am Dienstag, 20. September 2016, 11:36:41 CEST schrieb Peter Chen:
> > > We have an well-known problem that the device needs to do some power
> > > sequence before it can be recognized by related host, the typical
> > > example like hard-wired mmc devices and usb devices.
> > > 
> > > This power sequence is hard to be described at device tree and handled
> > > by
> > > related host driver, so we have created a common power sequence
> > > library to cover this requirement. The core code has supplied
> > > some common helpers for host driver, and individual power sequence
> > > libraries handle kinds of power sequence for devices.
> > > 
> > > pwrseq_generic is intended for general purpose of power sequence, which
> > > handles gpios and clocks currently, and can cover regulator and pinctrl
> > > in future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off
> > > if only one power sequence is needed, else call of_pwrseq_on_list
> > > /of_pwrseq_off_list instead (eg, USB hub driver).
> > > 
> > > Signed-off-by: Peter Chen 
> > > Tested-by Joshua Clayton 
> > > Reviewed-by: Matthias Kaehlcke 
> > > Tested-by: Matthias Kaehlcke 
> > 
> > first of all, glad to see this move forward. I've only some qualms with
> > the
> > static number of allocated power sequences below.
> 
> Thanks for commenting it, the preallocate way is not a good way, but I
> can't find suitable way. See below comments.
> 
> > > +static int __init pwrseq_generic_register(void)
> > > +{
> > > + struct pwrseq_generic *pwrseq_gen;
> > > + int i;
> > > +
> > > + for (i = 0; i < CONFIG_PWRSEQ_GENERIC_INSTANCE_NUMBER; i++) {
> > > + pwrseq_gen = kzalloc(sizeof(*pwrseq_gen), GFP_KERNEL);
> > > + if (!pwrseq_gen)
> > > + return -ENOMEM;
> > > +
> > > + pwrseq_gen->pwrseq.pwrseq_of_match_table = generic_id_table;
> > > + pwrseq_gen->pwrseq.get = pwrseq_generic_get;
> > > + pwrseq_gen->pwrseq.on = pwrseq_generic_on;
> > > + pwrseq_gen->pwrseq.off = pwrseq_generic_off;
> > > + pwrseq_gen->pwrseq.put = pwrseq_generic_put;
> > > + pwrseq_gen->pwrseq.free = pwrseq_generic_free;
> > > +
> > > + pwrseq_register(_gen->pwrseq);
> > > + }
> > > +
> > > + return 0;
> > > +}
> > > +postcore_initcall(pwrseq_generic_register)
> > 
> > I see that you need to have it preallocated for the compatible matching,
> > but wouldn't it also work to either just register the type and allocate
> > dynamically or otherwise just allocate a new spare everytime
> > pwrseq_generic_get() picks up the previous spare?
> 
> Before compatible matching, the host driver doesn't know which pwrseq type
> for its child node, then doesn't know which pwrseq instance needs to be
> allocated. From dts, we don't know which pwrseq type for the node.

yes, that is why I was suggesting allocating one (or two) here in 
pwrseq_generic_register() and every time pwrseq_generic_get() grabs the last 
free sequence instance, you allocate a new free spare one in that function.
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Re: [PATCH v7 2/8] power: add power sequence library

[Peter Chen]

On Wed, Oct 12, 2016 at 12:30:29PM +0200, Heiko Stuebner wrote:
> Hi,
> 
> Am Dienstag, 20. September 2016, 11:36:41 CEST schrieb Peter Chen:
> > We have an well-known problem that the device needs to do some power
> > sequence before it can be recognized by related host, the typical
> > example like hard-wired mmc devices and usb devices.
> > 
> > This power sequence is hard to be described at device tree and handled by
> > related host driver, so we have created a common power sequence
> > library to cover this requirement. The core code has supplied
> > some common helpers for host driver, and individual power sequence
> > libraries handle kinds of power sequence for devices.
> > 
> > pwrseq_generic is intended for general purpose of power sequence, which
> > handles gpios and clocks currently, and can cover regulator and pinctrl
> > in future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off
> > if only one power sequence is needed, else call of_pwrseq_on_list
> > /of_pwrseq_off_list instead (eg, USB hub driver).
> >
> > Signed-off-by: Peter Chen 
> > Tested-by Joshua Clayton 
> > Reviewed-by: Matthias Kaehlcke 
> > Tested-by: Matthias Kaehlcke 
> 
> first of all, glad to see this move forward. I've only some qualms with the 
> static number of allocated power sequences below.
> 

Thanks for commenting it, the preallocate way is not a good way, but I
can't find suitable way. See below comments.

> > +static int __init pwrseq_generic_register(void)
> > +{
> > +   struct pwrseq_generic *pwrseq_gen;
> > +   int i;
> > +
> > +   for (i = 0; i < CONFIG_PWRSEQ_GENERIC_INSTANCE_NUMBER; i++) {
> > +   pwrseq_gen = kzalloc(sizeof(*pwrseq_gen), GFP_KERNEL);
> > +   if (!pwrseq_gen)
> > +   return -ENOMEM;
> > +
> > +   pwrseq_gen->pwrseq.pwrseq_of_match_table = generic_id_table;
> > +   pwrseq_gen->pwrseq.get = pwrseq_generic_get;
> > +   pwrseq_gen->pwrseq.on = pwrseq_generic_on;
> > +   pwrseq_gen->pwrseq.off = pwrseq_generic_off;
> > +   pwrseq_gen->pwrseq.put = pwrseq_generic_put;
> > +   pwrseq_gen->pwrseq.free = pwrseq_generic_free;
> > +
> > +   pwrseq_register(_gen->pwrseq);
> > +   }
> > +
> > +   return 0;
> > +}
> > +postcore_initcall(pwrseq_generic_register)
> 
> I see that you need to have it preallocated for the compatible matching, but 
> wouldn't it also work to either just register the type and allocate 
> dynamically or otherwise just allocate a new spare everytime 
> pwrseq_generic_get() picks up the previous spare?

Before compatible matching, the host driver doesn't know which pwrseq type
for its child node, then doesn't know which pwrseq instance needs to be
allocated. From dts, we don't know which pwrseq type for the node.

-- 

Best Regards,
Peter Chen
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Re: [PATCH v7 2/8] power: add power sequence library

[Heiko Stuebner]

Hi,

Am Dienstag, 20. September 2016, 11:36:41 CEST schrieb Peter Chen:
> We have an well-known problem that the device needs to do some power
> sequence before it can be recognized by related host, the typical
> example like hard-wired mmc devices and usb devices.
> 
> This power sequence is hard to be described at device tree and handled by
> related host driver, so we have created a common power sequence
> library to cover this requirement. The core code has supplied
> some common helpers for host driver, and individual power sequence
> libraries handle kinds of power sequence for devices.
> 
> pwrseq_generic is intended for general purpose of power sequence, which
> handles gpios and clocks currently, and can cover regulator and pinctrl
> in future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off
> if only one power sequence is needed, else call of_pwrseq_on_list
> /of_pwrseq_off_list instead (eg, USB hub driver).
>
> Signed-off-by: Peter Chen 
> Tested-by Joshua Clayton 
> Reviewed-by: Matthias Kaehlcke 
> Tested-by: Matthias Kaehlcke 

first of all, glad to see this move forward. I've only some qualms with the 
static number of allocated power sequences below.

[...]

> diff --git a/drivers/power/pwrseq/Kconfig b/drivers/power/pwrseq/Kconfig
> new file mode 100644
> index 000..dff5e35
> --- /dev/null
> +++ b/drivers/power/pwrseq/Kconfig
> @@ -0,0 +1,45 @@
> +#
> +# Power Sequence library
> +#
> +
> +config POWER_SEQUENCE
> + bool
> +
> +menu "Power Sequence Support"
> +
> +config PWRSEQ_GENERIC
> + bool "Generic power sequence control"
> + depends on OF
> + select POWER_SEQUENCE
> + help
> +It is used for drivers which needs to do power sequence
> +(eg, turn on clock, toggle reset gpio) before the related
> +devices can be found by hardware. This generic one can be
> +used for common power sequence control.
> +
> +config PWRSEQ_GENERIC_INSTANCE_NUMBER
> + int "Number of Generic Power Sequence Instance"
> + depends on PWRSEQ_GENERIC
> + range 1 10
> + default 2
> + help
> +Usually, there are not so many devices needs power sequence, we set 
> two
> +as default value.

limiting this to some arbitary compile-time number somehow seems crippling for 
the single-image approach. I.e. a distribution might select something and 
during its lifetime the board requiring n+1 power-sequences appears and thus 
needs a different kernel version just to support that additional sequence.

Also, board designers are creative, and there were already complex examples 
mentioned elsewhere, so nothing keeps people from inventing something even 
more complex.

[...]

> diff --git a/drivers/power/pwrseq/pwrseq_generic.c
> b/drivers/power/pwrseq/pwrseq_generic.c new file mode 100644
> index 000..bcd16c3
> --- /dev/null
> +++ b/drivers/power/pwrseq/pwrseq_generic.c

[...]

> +static int pwrseq_generic_get(struct device_node *np, struct pwrseq
> *pwrseq) +{
> + struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
> + enum of_gpio_flags flags;
> + int reset_gpio, clk, ret = 0;
> +
> + for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++) {
> + pwrseq_gen->clks[clk] = of_clk_get(np, clk);
> + if (IS_ERR(pwrseq_gen->clks[clk])) {
> + ret = PTR_ERR(pwrseq_gen->clks[clk]);
> + if (ret != -ENOENT)
> + goto err_put_clks;
> + pwrseq_gen->clks[clk] = NULL;
> + break;
> + }
> + }
> +
> + reset_gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, );
> + if (gpio_is_valid(reset_gpio)) {
> + unsigned long gpio_flags;
> +
> + if (flags & OF_GPIO_ACTIVE_LOW)
> + gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_LOW;
> + else
> + gpio_flags = GPIOF_OUT_INIT_HIGH;
> +
> + ret = gpio_request_one(reset_gpio, gpio_flags,
> + "pwrseq-reset-gpios");
> + if (ret)
> + goto err_put_clks;
> +
> + pwrseq_gen->gpiod_reset = gpio_to_desc(reset_gpio);
> + of_property_read_u32(np, "reset-duration-us",
> + _gen->duration_us);
> + } else {
> + if (reset_gpio == -ENOENT)
> + return 0;
> +
> + ret = reset_gpio;
> + pr_err("Failed to get reset gpio on %s, err = %d\n",
> + np->full_name, reset_gpio);
> + goto err_put_clks;
> + }
> +
> + return ret;
> +
> +err_put_clks:
> + while (--clk >= 0)
> + clk_put(pwrseq_gen->clks[clk]);
> + return ret;
> +}
> +
> +static const struct of_device_id generic_id_table[] = {
> + { .compatible = "generic",},
> + { /* sentinel */ }
> +};
> +
> 

[PATCH v7 2/8] power: add power sequence library

[Peter Chen]

We have an well-known problem that the device needs to do some power
sequence before it can be recognized by related host, the typical
example like hard-wired mmc devices and usb devices.

This power sequence is hard to be described at device tree and handled by
related host driver, so we have created a common power sequence
library to cover this requirement. The core code has supplied
some common helpers for host driver, and individual power sequence
libraries handle kinds of power sequence for devices.

pwrseq_generic is intended for general purpose of power sequence, which
handles gpios and clocks currently, and can cover regulator and pinctrl
in future. The host driver just needs to call of_pwrseq_on/of_pwrseq_off
if only one power sequence is needed, else call of_pwrseq_on_list
/of_pwrseq_off_list instead (eg, USB hub driver).

Signed-off-by: Peter Chen 
Tested-by Joshua Clayton 
Reviewed-by: Matthias Kaehlcke 
Tested-by: Matthias Kaehlcke 
---
 MAINTAINERS |   9 ++
 drivers/power/Kconfig   |   1 +
 drivers/power/Makefile  |   1 +
 drivers/power/pwrseq/Kconfig|  45 ++
 drivers/power/pwrseq/Makefile   |   3 +
 drivers/power/pwrseq/core.c | 190 
 drivers/power/pwrseq/pwrseq_compatible_sample.c | 178 ++
 drivers/power/pwrseq/pwrseq_generic.c   | 177 ++
 include/linux/power/pwrseq.h|  73 +
 9 files changed, 677 insertions(+)
 create mode 100644 drivers/power/pwrseq/Kconfig
 create mode 100644 drivers/power/pwrseq/Makefile
 create mode 100644 drivers/power/pwrseq/core.c
 create mode 100644 drivers/power/pwrseq/pwrseq_compatible_sample.c
 create mode 100644 drivers/power/pwrseq/pwrseq_generic.c
 create mode 100644 include/linux/power/pwrseq.h

diff --git a/MAINTAINERS b/MAINTAINERS
index b3e9395..b353769 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9343,6 +9343,15 @@ F:   include/linux/pm_*
 F: include/linux/powercap.h
 F: drivers/powercap/
 
+POWER SEQUENCE LIBRARY
+M: Peter Chen 
+T: git git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb.git
+L: linux...@vger.kernel.org
+S: Maintained
+F: Documentation/devicetree/bindings/power/pwrseq/
+F: drivers/power/pwrseq/
+F: include/linux/power/pwrseq.h/
+
 POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS
 M: Sebastian Reichel 
 M: Dmitry Eremin-Solenikov 
diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index acd4a15..f6aa4fd 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -515,3 +515,4 @@ endif # POWER_SUPPLY
 
 source "drivers/power/reset/Kconfig"
 source "drivers/power/avs/Kconfig"
+source "drivers/power/pwrseq/Kconfig"
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index e46b75d..4ed2e12 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -74,3 +74,4 @@ obj-$(CONFIG_CHARGER_TPS65217)+= tps65217_charger.o
 obj-$(CONFIG_POWER_RESET)  += reset/
 obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
 obj-$(CONFIG_AXP288_CHARGER)   += axp288_charger.o
+obj-$(CONFIG_POWER_SEQUENCE)   += pwrseq/
diff --git a/drivers/power/pwrseq/Kconfig b/drivers/power/pwrseq/Kconfig
new file mode 100644
index 000..dff5e35
--- /dev/null
+++ b/drivers/power/pwrseq/Kconfig
@@ -0,0 +1,45 @@
+#
+# Power Sequence library
+#
+
+config POWER_SEQUENCE
+   bool
+
+menu "Power Sequence Support"
+
+config PWRSEQ_GENERIC
+   bool "Generic power sequence control"
+   depends on OF
+   select POWER_SEQUENCE
+   help
+  It is used for drivers which needs to do power sequence
+  (eg, turn on clock, toggle reset gpio) before the related
+  devices can be found by hardware. This generic one can be
+  used for common power sequence control.
+
+config PWRSEQ_GENERIC_INSTANCE_NUMBER
+   int "Number of Generic Power Sequence Instance"
+   depends on PWRSEQ_GENERIC
+   range 1 10
+   default 2
+   help
+  Usually, there are not so many devices needs power sequence, we set 
two
+  as default value.
+
+config PWRSEQ_SAMPLE
+   bool "sample power sequence control using compatible string"
+   depends on OF
+   select POWER_SEQUENCE
+   help
+  It is a sample library which implements power sequence for device id,
+  it is an example purpose.
+
+config PWRSEQ_SAMPLE_INSTANCE_NUMBER
+   int "Number of Sample Power Sequence Instance"
+   depends on PWRSEQ_SAMPLE
+   range 1 5
+   default 1
+   help
+  Usually, this file is special for certain device, so the default for 
this number
+  is 1.
+endmenu
diff --git a/drivers/power/pwrseq/Makefile