linux-kernel - Re: [PATCH v4 5/9] gpio: Add new gpio-macsmc driver for Apple Macs

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Message-Id: <b96bd2d6-98f7-44da-9293-816daeac80d0@app.fastmail.com>
Date: Tue, 06 May 2025 12:16:06 +0200
From: "Sven Peter" <sven@...npeter.dev>
To: "Bartosz Golaszewski" <brgl@...ev.pl>
Cc: "Janne Grunau" <j@...nau.net>, "Alyssa Rosenzweig" <alyssa@...enzweig.io>,
 "Neal Gompa" <neal@...pa.dev>, "Hector Martin" <marcan@...can.st>,
 "Linus Walleij" <linus.walleij@...aro.org>, "Rob Herring" <robh@...nel.org>,
 "Krzysztof Kozlowski" <krzk+dt@...nel.org>,
 "Conor Dooley" <conor+dt@...nel.org>, "Sebastian Reichel" <sre@...nel.org>,
 "Lee Jones" <lee@...nel.org>, "Marc Zyngier" <maz@...nel.org>,
 "Russell King" <rmk+kernel@...linux.org.uk>, asahi@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org,
 "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org
Subject: Re: [PATCH v4 5/9] gpio: Add new gpio-macsmc driver for Apple Macs

Hi,


On Tue, May 6, 2025, at 10:07, Bartosz Golaszewski wrote:
> On Sat, May 3, 2025 at 12:07 PM Sven Peter via B4 Relay
> <devnull+sven.svenpeter.dev@...nel.org> wrote:
>>
>> From: Hector Martin <marcan@...can.st>
>>
>> This driver implements the GPIO service on top of the SMC framework
>> on Apple Mac machines. In particular, these are the GPIOs present in the
>> PMU IC which are used to control power to certain on-board devices.
>>
>> Although the underlying hardware supports various pin config settings
>> (input/output, open drain, etc.), this driver does not implement that
>> functionality and leaves it up to the firmware to configure things
>> properly. We also don't yet support interrupts/events. This is
>> sufficient for device power control, which is the only thing we need to
>> support at this point. More features will be implemented when needed.
>>
>> To our knowledge, only Apple Silicon Macs implement this SMC feature.
>>
>> Signed-off-by: Hector Martin <marcan@...can.st>
>> Reviewed-by: Bartosz Golaszewski <brgl@...ev.pl>
>> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
>> Reviewed-by: Sven Peter <sven@...npeter.dev>
>> Signed-off-by: Russell King (Oracle) <rmk+kernel@...linux.org.uk>
>> Signed-off-by: Sven Peter <sven@...npeter.dev>
>> ---
>
> [snip]
>
>> +
>> +       smcgp->gc.label = "macsmc-pmu-gpio";
>> +       smcgp->gc.owner = THIS_MODULE;
>> +       smcgp->gc.get = macsmc_gpio_get;
>> +       smcgp->gc.set = macsmc_gpio_set;
>
> I must have given my Reviewed-by under this driver before we started
> the conversion to the new GPIO driver setters. Could you please
> replace this with set_rv() as the old set() is now deprecated?

Probably, the last version I took from the ML is from November 2022 :-(
Will do that for the next version, I can just pass through the return value
we get from apple_smc_write_u32 anyway.


Thanks,


Sven


-- >8 --
Subject: [PATCH] fixup! gpio: Add new gpio-macsmc driver for Apple Macs

---
 drivers/gpio/gpio-macsmc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-macsmc.c b/drivers/gpio/gpio-macsmc.c
index 289be4268f63..a68676239718 100644
--- a/drivers/gpio/gpio-macsmc.c
+++ b/drivers/gpio/gpio-macsmc.c
@@ -135,7 +135,7 @@ static int macsmc_gpio_get(struct gpio_chip *gc, unsigned int offset)
 	return val ? 1 : 0;
 }

-static void macsmc_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
+static int macsmc_gpio_set(struct gpio_chip *gc, unsigned int offset, int value)
 {
 	struct macsmc_gpio *smcgp = gpiochip_get_data(gc);
 	smc_key key = macsmc_gpio_key(offset);
@@ -146,6 +146,8 @@ static void macsmc_gpio_set(struct gpio_chip *gc, unsigned int offset, int value
 	if (ret < 0)
 		dev_err(smcgp->dev, "GPIO set failed %p4ch = 0x%x\n",
 			&key, value);
+
+	return ret;
 }

 static int macsmc_gpio_init_valid_mask(struct gpio_chip *gc,
@@ -214,7 +216,7 @@ static int macsmc_gpio_probe(struct platform_device *pdev)
 	smcgp->gc.label = "macsmc-pmu-gpio";
 	smcgp->gc.owner = THIS_MODULE;
 	smcgp->gc.get = macsmc_gpio_get;
-	smcgp->gc.set = macsmc_gpio_set;
+	smcgp->gc.set_rv = macsmc_gpio_set;
 	smcgp->gc.get_direction = macsmc_gpio_get_direction;
 	smcgp->gc.init_valid_mask = macsmc_gpio_init_valid_mask;
 	smcgp->gc.can_sleep = true;
--
2.34.1