Re: [PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
Hi Again Andy, On Fri, 2021-03-26 at 19:51 +0200, Andy Shevchenko wrote: > On Fri, Mar 26, 2021 at 3:33 PM Matti Vaittinen > wrote: > > On Fri, 2021-03-26 at 13:26 +0200, Andy Shevchenko wrote: > > > On Wed, Mar 24, 2021 at 12:20 PM Matti Vaittinen > > > wrote: > > > > > > + if (!bd71815->e5_pin_is_gpo && offset) > > > > + return; > > > > > > I wonder if you can use valid_mask instead of this. > > > > Do you mean re-naming the e5_pin_is_gpo to valid_mask? Or do you > > mean > > some GPIO framework internal feature allowing to define valid pins? > > (If > > my memory serves me right one can set invalid pins from DT - but by > > default all pins are valid and here we want to invalidate a pin by > > default). For renaming I don't see the value - if internal feature > > can > > be used then there may be value. Thanks for the pointer, I'll look > > what > > I find. > > I mean to utilize internal valid_mask bitmap. Yes, you may fill it as > valid at the start of the driver and then simply call __clear_bit() / > clear_bit() against one you wanted to disable. Then core will take > care of the rest (AFAIR). Right. I see there is the init_valid_mask callback which could be populated. OTOH, I think this check is actually not needed at all if we set the ngpios based on the DT flag. The check in set/get functions was just a symptom of my paranoia. Anyways, I owe you as I just learned something new :) > > > > + int ret; > > > > + struct bd71815_gpio *g; > > > > + struct device *dev; > > > > + struct device *parent; > ... > > > > > + parent = dev->parent; > > > > It is not always obvious (especially for someone not reading MFD > > driver > > code frequently) why we use parent device for some things and the > > device being probed to some other stuff. Typically this is not > > needed > > if the device is not MFD sub-device. And again, the comments in the > > middle of declaration block look confusing to me. I think removing > > comments and moving these to declaration make readability _much_ > > worse. > > I disagree with you here again. To me it's like completely unneeded > churn. > I've seen even experienced developers making mistakes by binding the lifetime of sub-device stuff to parent device's lifetime. I've also seen even experienced developers who haven't used to dealing with MFD getting confused when they see parent device's dt-node or regmap being used. My view on this is that if the comment helps next reader to avoid a mistake or understand why something is done - then it is worthy. I have rarely seen comments which make code less readable or understandable. > > > > + g->chip.of_node = parent->of_node; > > > > > > Redundant. GPIO library does it for you and even better. > > > > So I can nowadays just omit this? Thanks! > > For a long time. I haven't checked the date when it started like > this, > but couple of years sounds like a good approximation. Ok. Thanks for pointing it out. Best Regards Matti Vaittinen
Re: [PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
On Fri, Mar 26, 2021 at 3:33 PM Matti Vaittinen wrote: > On Fri, 2021-03-26 at 13:26 +0200, Andy Shevchenko wrote: > > On Wed, Mar 24, 2021 at 12:20 PM Matti Vaittinen > > wrote: ... > > > + return (val >> offset) & 1; > > > > !!(val & BIT(offset)) can also work and be in alignment with the > > below code. > > This is an opinion, but to me !!(val & BIT(offset)) looks more > confusing. I don't see the benefit from the change. I always try to find a compromise between two: your own style and common practice used in the subsystem in question. AFAIR my proposal is (recommended?) style for new code. ... > > > + if (!bd71815->e5_pin_is_gpo && offset) > > > + return; > > > > I wonder if you can use valid_mask instead of this. > > Do you mean re-naming the e5_pin_is_gpo to valid_mask? Or do you mean > some GPIO framework internal feature allowing to define valid pins? (If > my memory serves me right one can set invalid pins from DT - but by > default all pins are valid and here we want to invalidate a pin by > default). For renaming I don't see the value - if internal feature can > be used then there may be value. Thanks for the pointer, I'll look what > I find. I mean to utilize internal valid_mask bitmap. Yes, you may fill it as valid at the start of the driver and then simply call __clear_bit() / clear_bit() against one you wanted to disable. Then core will take care of the rest (AFAIR). ... > > > + bit = BIT(offset); > > > > Can be moved to the definition block. > > I don't like doing the assignment before we check if the operation is > valid. And, making assignments which are not plain constants in > declaration make reading the declaration much harder. OK. ... > > > + default: > > > + break; > > > + } > > > + return -EOPNOTSUPP; > > > > You may return directly from default. > > I think there used to be compilers which didn't like having the return > inside a block - even if the block was a default. I also prefer seeing > return at the end of function which should return a value. I prefer less LOCs in the file when it makes sense. And here you seem appealing to compilers from last century. ... > > > + int ret; > > > + struct bd71815_gpio *g; > > > + struct device *dev; > > > + struct device *parent; > > > > Reversed xmas tree order. > > What is the added value here? I understand alphabetical sorting - it > helps looking if particular entry is included. I also understand type- > based sorting. But reverse Xmas tree? I thin I have heard it eases > reading declarations - which is questionable in this case. Double so > when you also suggest moving assignments to declaration block which > makes it _much_ harder to read? I won't change this unless it is > mandated by the maintainers. Compare to: struct bd71815_gpio *g; struct device *parent; struct device *dev; int ret; It's easier to read, esp. taking into account that ret is going last. It seems to me more natural, so we have a disagreement here, but I'm not a maintainer, it's up to them. ... > > > + parent = dev->parent; > > It is not always obvious (especially for someone not reading MFD driver > code frequently) why we use parent device for some things and the > device being probed to some other stuff. Typically this is not needed > if the device is not MFD sub-device. And again, the comments in the > middle of declaration block look confusing to me. I think removing > comments and moving these to declaration make readability _much_ worse. I disagree with you here again. To me it's like completely unneeded churn. ... > > > + g->e5_pin_is_gpo = of_property_read_bool(parent->of_node, > > > +"rohm,enable- > > > hidden-gpo"); > > > > You may use device_property_read_bool(). > > Out of the curiosity - is there any other reason but ACPI? We might have another property provider (by the fact we already have the third one, but it's a specific one, called software nodes). > ACPI support > can be added later if needed. Yes, but doing something OF centric which might have been used on non-OF platforms is to do double effort and waste time and resources. > I still think you're correct. This is > definitely one of the points that fall in the category of things "I > must consider as a good practice for (my) new contribution". So I try > to keep this in mind in the future. ... > > > + g->chip.of_node = parent->of_node; > > > > Redundant. GPIO library does it for you and even better. > > So I can nowadays just omit this? Thanks! For a long time. I haven't checked the date when it started like this, but couple of years sounds like a good approximation. ... > > > +MODULE_DEVICE_TABLE(platform, bd7181x_gpo_id); > > > > Why do you need this ID table exactly? > > You have the same name as in the platform driver structure below. > > This driver was also supporting anothe
Re: [PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
Hi Andy, On Fri, 2021-03-26 at 13:26 +0200, Andy Shevchenko wrote: > On Wed, Mar 24, 2021 at 12:20 PM Matti Vaittinen > wrote: > > Support GPO(s) found from ROHM BD71815 power management IC. The IC > > has two > > GPO pins but only one is properly documented in data-sheet. The > > driver > > in the datasheet > > > exposes by default only the documented GPO. The second GPO is > > connected to > > E5 pin and is marked as GND in data-sheet. Control for this > > undocumented > > in the datasheet > > > pin can be enabled using a special DT property. > > > > This driver is derived from work by Peter Yang < > > yang...@embest-tech.com> > > although not so much of original is left. > > of the original > > Below my comments independently on the fact if this driver will be > completely rewritten, consider them as a good practice for your new > contribution. Thank you for the review. I appreciate your help although I don't always agree necessity regarding all of the styling suggestions :) I did not respond here to the suggestions I agreed with. As Linus pointed out, few of the ROHM drivers should be revised for regmap_gpio usage in near future. I will definitely go through all the comments at that point if there is no reason to respin series earlier. > + int val; > > + > > + ret = regmap_read(bd71815->regmap, BD71815_REG_GPO, &val); > > + if (ret) > > + return ret; > > + return (val >> offset) & 1; > > !!(val & BIT(offset)) can also work and be in alignment with the > below code. This is an opinion, but to me !!(val & BIT(offset)) looks more confusing. I don't see the benefit from the change. > > ... > > > + if (!bd71815->e5_pin_is_gpo && offset) > > + return; > > I wonder if you can use valid_mask instead of this. Do you mean re-naming the e5_pin_is_gpo to valid_mask? Or do you mean some GPIO framework internal feature allowing to define valid pins? (If my memory serves me right one can set invalid pins from DT - but by default all pins are valid and here we want to invalidate a pin by default). For renaming I don't see the value - if internal feature can be used then there may be value. Thanks for the pointer, I'll look what I find. > > ... > > > + bit = BIT(offset); > > Can be moved to the definition block. I don't like doing the assignment before we check if the operation is valid. And, making assignments which are not plain constants in declaration make reading the declaration much harder. > ... > > > + default: > > + break; > > + } > > + return -EOPNOTSUPP; > > You may return directly from default. I think there used to be compilers which didn't like having the return inside a block - even if the block was a default. I also prefer seeing return at the end of function which should return a value. > > ... > > > + int ret; > > + struct bd71815_gpio *g; > > + struct device *dev; > > + struct device *parent; > > Reversed xmas tree order. What is the added value here? I understand alphabetical sorting - it helps looking if particular entry is included. I also understand type- based sorting. But reverse Xmas tree? I thin I have heard it eases reading declarations - which is questionable in this case. Double so when you also suggest moving assignments to declaration block which makes it _much_ harder to read? I won't change this unless it is mandated by the maintainers. > > ... > > > + /* > > +* Bind devm lifetime to this platform device => use dev > > for devm. > > +* also the prints should originate from this device. > > +*/ > > Why is this comment needed? > > > > + /* The device-tree and regmap come from MFD => use parent > > for that */ > > Why do you need this comment? > > > + parent = dev->parent; It is not always obvious (especially for someone not reading MFD driver code frequently) why we use parent device for some things and the device being probed to some other stuff. Typically this is not needed if the device is not MFD sub-device. And again, the comments in the middle of declaration block look confusing to me. I think removing comments and moving these to declaration make readability _much_ worse. > ... > > > + g->e5_pin_is_gpo = of_property_read_bool(parent->of_node, > > +"rohm,enable- > > hidden-gpo"); > > You may use device_property_read_bool(). Out of the curiosity - is there any other reason but ACPI? ACPI support can be added later if needed. I still think you're correct. This is definitely one of the points that fall in the category of things "I must consider as a good practice for (my) new contribution". So I try to keep this in mind in the future. > > + g->chip.of_node = parent->of_node; > > Redundant. GPIO library does it for you and even better. So I can nowadays just omit this? Thanks! > > + ret = devm_gpiochip_add_data(
Re: [PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
On Fri, Mar 26, 2021 at 1:26 PM Andy Shevchenko wrote: > On Wed, Mar 24, 2021 at 12:20 PM Matti Vaittinen > wrote: > > +#include > > You may do better than be OF-centric. See below. Ah, yep, when you switch to unified device property API, you would need property.h and mod_devicetable.h instead of this. -- With Best Regards, Andy Shevchenko
Re: [PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
On Wed, Mar 24, 2021 at 12:20 PM Matti Vaittinen
wrote:
>
> Support GPO(s) found from ROHM BD71815 power management IC. The IC has two
> GPO pins but only one is properly documented in data-sheet. The driver
in the datasheet
> exposes by default only the documented GPO. The second GPO is connected to
> E5 pin and is marked as GND in data-sheet. Control for this undocumented
in the datasheet
> pin can be enabled using a special DT property.
>
> This driver is derived from work by Peter Yang
> although not so much of original is left.
of the original
Below my comments independently on the fact if this driver will be
completely rewritten, consider them as a good practice for your new
contribution.
...
> +/*
> + * Support to GPOs on ROHM BD71815
> + */
This is effectively one line.
...
> +/* For the BD71815 register definitions */
> +#include
Since it's component specific header(s) I would move it to a separate
group and locate...
> +#include
> +#include
You may do better than be OF-centric. See below.
> +#include
> +
...somewhere here.
...
> + /*
> +* Sigh. The BD71815 and BD71817 were originally designed to support
> two
> +* GPO pins. At some point it was noticed the second GPO pin which is
> +* the E5 pin located at the center of IC is hard to use on PCB (due
> to
> +* the location). It was decided to not promote this second GPO and
> pin
> +* is marked as GND on the data-sheet. The functionality is still
> there
> +* though! I guess driving GPO connected to ground is a bad idea. Thus
a GPO
to the ground
> +* we do not support it by default. OTOH - the original driver written
> +* by colleagues at Embest did support controlling this second GPO. It
> +* is thus possible this is used in some of the products.
> +*
> +* This driver does not by default support configuring this second GPO
> +* but allows using it by providing the DT property
> +* "rohm,enable-hidden-gpo".
> +*/
...
> + int ret = 0;
Redundant assignment.
> + int val;
> +
> + ret = regmap_read(bd71815->regmap, BD71815_REG_GPO, &val);
> + if (ret)
> + return ret;
> + return (val >> offset) & 1;
!!(val & BIT(offset)) can also work and be in alignment with the below code.
...
> + if (!bd71815->e5_pin_is_gpo && offset)
> + return;
I wonder if you can use valid_mask instead of this.
...
> + bit = BIT(offset);
Can be moved to the definition block.
...
> + if (!bdgpio->e5_pin_is_gpo && offset)
> + return -EOPNOTSUPP;
As above.
...
> + default:
> + break;
> + }
> + return -EOPNOTSUPP;
You may return directly from default.
...
> + int ret;
> + struct bd71815_gpio *g;
> + struct device *dev;
> + struct device *parent;
Reversed xmas tree order.
...
> + /*
> +* Bind devm lifetime to this platform device => use dev for devm.
> +* also the prints should originate from this device.
> +*/
Why is this comment needed?
...
> + dev = &pdev->dev;
Can be done in the definition block.
...
> + /* The device-tree and regmap come from MFD => use parent for that */
Why do you need this comment?
> + parent = dev->parent;
Ditto, can be moved to the definition block.
...
> + g->e5_pin_is_gpo = of_property_read_bool(parent->of_node,
> +"rohm,enable-hidden-gpo");
You may use device_property_read_bool().
...
> + g->chip.of_node = parent->of_node;
Redundant. GPIO library does it for you and even better.
...
> + ret = devm_gpiochip_add_data(dev, &g->chip, g);
> + if (ret < 0) {
> + dev_err(dev, "could not register gpiochip, %d\n", ret);
> + return ret;
> + }
> +
> + return ret;
It's as simply as
return devm_gpiochip_add_data(...);
...
> +static const struct platform_device_id bd7181x_gpo_id[] = {
> + { "bd71815-gpo" },
> + { },
No comma for the terminator line.
> +};
> +MODULE_DEVICE_TABLE(platform, bd7181x_gpo_id);
Why do you need this ID table exactly?
You have the same name as in the platform driver structure below.
> +static struct platform_driver gpo_bd71815_driver = {
> + .driver = {
> + .name = "bd71815-gpo",
> + .owner = THIS_MODULE,
This is done by module_*_driver() macros, drop it.
> + },
> + .probe = gpo_bd71815_probe,
> + .id_table = bd7181x_gpo_id,
> +};
> +
Extra blank line.
> +module_platform_driver(gpo_bd71815_driver);
> +/* Note: this hardware lives inside an I2C-based multi-function device. */
> +MODULE_ALIAS("platform:bd71815-gpo");
> +
Ditto.
> +MODULE_AUTHOR("Peter Yang ");
And I don't see a match with a committer/submitter/co-developer/etc.
Please, make corresponding fields
Re: [PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
Hello Linus, On Thu, 2021-03-25 at 10:35 +0100, Linus Walleij wrote: > On Wed, Mar 24, 2021 at 8:29 AM Matti Vaittinen > wrote: > > > Support GPO(s) found from ROHM BD71815 power management IC. The IC > > has two > > GPO pins but only one is properly documented in data-sheet. The > > driver > > exposes by default only the documented GPO. The second GPO is > > connected to > > E5 pin and is marked as GND in data-sheet. Control for this > > undocumented > > pin can be enabled using a special DT property. > > > > This driver is derived from work by Peter Yang < > > yang...@embest-tech.com> > > although not so much of original is left. > > > > Signed-off-by: Matti Vaittinen > > --- > > Changes since v3: > > - No changes > > This looks OK to me: > Acked-by: Linus Walleij > > It could potentially (like the other Rohm GPIO MFD PMIC drivers) > make some use of the gpio regmap library, but we have some > pending changes for that so look into it after the next merge > window. > > I.e. for your TODO: look at the GPIO_REGMAP helper. I just took a quick peek at gpio_regmap and it looks pretty good to me! Any particular reason why gpio_regmap is not just part of gpio_chip? I guess providing the 'gpio_regmap_direction_*()', 'gpio_regmap_get()', 'gpio_regmap_set()' as exported helpers and leaving calling the (devm_)gpiochip_add_data() to IC driver would have allowed more flexibility. Drivers could then use the gpio_regamap features which fit the IC (by providing pointers to helper functions in gpio_chip) - and handle potential oddball-features by using pointers to some customized functions in gpio_chip. Anyways, definitely worth getting familiar with! Thanks for the pointer :] Best Regards, Matti Vaittinen
Re: [PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
On Wed, Mar 24, 2021 at 8:29 AM Matti Vaittinen wrote: > Support GPO(s) found from ROHM BD71815 power management IC. The IC has two > GPO pins but only one is properly documented in data-sheet. The driver > exposes by default only the documented GPO. The second GPO is connected to > E5 pin and is marked as GND in data-sheet. Control for this undocumented > pin can be enabled using a special DT property. > > This driver is derived from work by Peter Yang > although not so much of original is left. > > Signed-off-by: Matti Vaittinen > --- > Changes since v3: > - No changes This looks OK to me: Acked-by: Linus Walleij It could potentially (like the other Rohm GPIO MFD PMIC drivers) make some use of the gpio regmap library, but we have some pending changes for that so look into it after the next merge window. I.e. for your TODO: look at the GPIO_REGMAP helper. Yours, Linus Walleij
[PATCH v4 09/16] gpio: support ROHM BD71815 GPOs
Support GPO(s) found from ROHM BD71815 power management IC. The IC has two
GPO pins but only one is properly documented in data-sheet. The driver
exposes by default only the documented GPO. The second GPO is connected to
E5 pin and is marked as GND in data-sheet. Control for this undocumented
pin can be enabled using a special DT property.
This driver is derived from work by Peter Yang
although not so much of original is left.
Signed-off-by: Matti Vaittinen
---
Changes since v3:
- No changes
drivers/gpio/Kconfig| 10 ++
drivers/gpio/Makefile | 1 +
drivers/gpio/gpio-bd71815.c | 176
3 files changed, 187 insertions(+)
create mode 100644 drivers/gpio/gpio-bd71815.c
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index e3607ec4c2e8..d3b3de514f6e 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1105,6 +1105,16 @@ config GPIO_BD70528
This driver can also be built as a module. If so, the module
will be called gpio-bd70528.
+config GPIO_BD71815
+ tristate "ROHM BD71815 PMIC GPIO support"
+ depends on MFD_ROHM_BD71828
+ help
+ Support for GPO(s) on ROHM BD71815 PMIC. There are two GPOs
+ available on the ROHM PMIC.
+
+ This driver can also be built as a module. If so, the module
+ will be called gpio-bd71815.
+
config GPIO_BD71828
tristate "ROHM BD71828 GPIO support"
depends on MFD_ROHM_BD71828
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index c58a90a3c3b1..4c12f31db31f 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_GPIO_ATH79) += gpio-ath79.o
obj-$(CONFIG_GPIO_BCM_KONA)+= gpio-bcm-kona.o
obj-$(CONFIG_GPIO_BCM_XGS_IPROC) += gpio-xgs-iproc.o
obj-$(CONFIG_GPIO_BD70528) += gpio-bd70528.o
+obj-$(CONFIG_GPIO_BD71815) += gpio-bd71815.o
obj-$(CONFIG_GPIO_BD71828) += gpio-bd71828.o
obj-$(CONFIG_GPIO_BD9571MWV) += gpio-bd9571mwv.o
obj-$(CONFIG_GPIO_BRCMSTB) += gpio-brcmstb.o
diff --git a/drivers/gpio/gpio-bd71815.c b/drivers/gpio/gpio-bd71815.c
new file mode 100644
index ..5552a23c8e53
--- /dev/null
+++ b/drivers/gpio/gpio-bd71815.c
@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Support to GPOs on ROHM BD71815
+ */
+
+#include
+#include
+#include
+/* For the BD71815 register definitions */
+#include
+#include
+#include
+#include
+
+struct bd71815_gpio {
+ struct gpio_chip chip;
+ struct device *dev;
+ struct regmap *regmap;
+ /*
+* Sigh. The BD71815 and BD71817 were originally designed to support two
+* GPO pins. At some point it was noticed the second GPO pin which is
+* the E5 pin located at the center of IC is hard to use on PCB (due to
+* the location). It was decided to not promote this second GPO and pin
+* is marked as GND on the data-sheet. The functionality is still there
+* though! I guess driving GPO connected to ground is a bad idea. Thus
+* we do not support it by default. OTOH - the original driver written
+* by colleagues at Embest did support controlling this second GPO. It
+* is thus possible this is used in some of the products.
+*
+* This driver does not by default support configuring this second GPO
+* but allows using it by providing the DT property
+* "rohm,enable-hidden-gpo".
+*/
+ bool e5_pin_is_gpo;
+};
+
+static int bd71815gpo_get(struct gpio_chip *chip, unsigned int offset)
+{
+ struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
+ int ret = 0;
+ int val;
+
+ ret = regmap_read(bd71815->regmap, BD71815_REG_GPO, &val);
+ if (ret)
+ return ret;
+
+ return (val >> offset) & 1;
+}
+
+static void bd71815gpo_set(struct gpio_chip *chip, unsigned int offset,
+ int value)
+{
+ struct bd71815_gpio *bd71815 = gpiochip_get_data(chip);
+ int ret, bit;
+
+ if (!bd71815->e5_pin_is_gpo && offset)
+ return;
+
+ bit = BIT(offset);
+
+ if (value)
+ ret = regmap_set_bits(bd71815->regmap, BD71815_REG_GPO, bit);
+ else
+ ret = regmap_clear_bits(bd71815->regmap, BD71815_REG_GPO, bit);
+
+ if (ret)
+ dev_warn(bd71815->dev, "failed to toggle GPO\n");
+}
+
+static int bd71815_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
+ unsigned long config)
+{
+ struct bd71815_gpio *bdgpio = gpiochip_get_data(chip);
+
+ if (!bdgpio->e5_pin_is_gpo && offset)
+ return -EOPNOTSUPP;
+
+ switch (pinconf_to_config_param(config)) {
+ case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+ return regmap_update_bits(bdgpio->regmap,
+ BD71815_REG_GPO,
