Re: [PATCH v2] gpio: winbond: add driver

["Maciej S. Szmigiero" <mail@xxxxxxxxxxxxxxxxxxxxx>]

On 28.12.2017 16:12, Andy Shevchenko wrote:
> On Fri, 2017-12-22 at 19:58 +0100, Maciej S. Szmigiero wrote:
>> This commit adds GPIO driver for Winbond Super I/Os.
>>
>> Currently, only W83627UHG model (also known as Nuvoton NCT6627UD) is
>> supported but in the future a support for other Winbond models, too,
>> can
>> be added to the driver.
>>
>> A module parameter "gpios" sets a bitmask of GPIO ports to enable (bit
>> 0 is
>> GPIO1, bit 1 is GPIO2, etc.).
>> One should be careful which ports one tinkers with since some might be
>> managed by the firmware (for functions like powering on and off,
>> sleeping,
>> BIOS recovery, etc.) and some of GPIO port pins are physically shared
>> with
>> other devices included in the Super I/O chip.
>  
>> +config GPIO_WINBOND
>> +	tristate "Winbond Super I/O GPIO support"
>> +	help
>> +	  This option enables support for GPIOs found on Winbond
>> Super I/O
>> +	  chips.
>> +	  Currently, only W83627UHG (also known as Nuvoton NCT6627UD)
>> is
>> +	  supported.
>> +
>> +	  You will need to provide a module parameter "gpios", or a
>> +	  boot-time parameter "gpio_winbond.gpios" with a bitmask of
>> GPIO
>> +	  ports to enable (bit 0 is GPIO1, bit 1 is GPIO2, etc.).
> 
> 1. Why it's required?

It is required bacause "[o]ne should be careful which ports one tinkers
with since some might be managed by the firmware (for functions like
powering on and off, sleeping, BIOS recovery, etc.) and some of GPIO port
pins are physically shared with other devices included in the Super I/O
chip".

> 2. GPIO1 -> GPIO0, GPIO2 -> GPIO1, etc ?

The chip datasheet calls GPIO devices and their pins "GPIO1", "GPIO2",
etc., however the driver uses a more common zero-based indexing (so,
for example, we don't waste the zeroth bit).

> 
>> +
>> +	  To compile this driver as a module, choose M here: the
>> module will
>> +	  be called gpio-winbond.
>>
> 
>> +#include <linux/errno.h>
>> +#include <linux/gpio.h>
>> +#include <linux/ioport.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
> 
> Perhaps, alphabetically ordered?

Isn't 'e' < 'g' < 'i' < 'm' < 'p' ?

BTW. The ISA bus version has slightly different includes.

> 
>> +
>> +#define WB_GPIO_DRIVER_NAME "gpio-winbond"
>> +
>> +#define WB_SIO_BASE 0x2e
>> +#define WB_SIO_BASE_HIGH 0x4e
> 
> Is it my mail client or you didn't use TAB(s) as separator?

Will use tabs as separators between name and value in this type of macro.

>> +#define WB_SIO_CHIP_ID_W83627UHG 0xa230
>> +#define WB_SIO_CHIP_ID_W83627UHG_MASK 0xfff0
> 
> GENMASK()

Ok.

>> +
>> +/* not an actual device number, just a value meaning 'no device' */
>> +#define WB_SIO_DEV_NONE 0xff
> 
> 
> 
>> +
>> +#define WB_SIO_DEV_UARTB 3
>> +#define WB_SIO_UARTB_REG_ENABLE 0x30
>> +#define WB_SIO_UARTB_ENABLE_ON 0
> 
> What does it mean?
> 
> 1. ???

Super I/O logical device number for UART B.

> 2. Register offset

(Device) enable register offset.

> 3. Bit to enable

(Device) enable register bit index.

> ?
> 
>> +
>> +#define WB_SIO_DEV_UARTC 6
>> +#define WB_SIO_UARTC_REG_ENABLE 0x30
>> +#define WB_SIO_UARTC_ENABLE_ON 0
>> +
>> +#define WB_SIO_DEV_GPIO34 7
>> +#define WB_SIO_GPIO34_REG_ENABLE 0x30
> 
>> +#define WB_SIO_GPIO34_ENABLE_4 1
>> +#define WB_SIO_GPIO34_ENABLE_3 0
> 
> Perhaps swap them?

Ok.
 
>> +#define WB_SIO_GPIO34_REG_IO3 0xe0
>> +#define WB_SIO_GPIO34_REG_DATA3 0xe1
>> +#define WB_SIO_GPIO34_REG_INV3 0xe2
>> +#define WB_SIO_GPIO34_REG_IO4 0xe4
>> +#define WB_SIO_GPIO34_REG_DATA4 0xe5
>> +#define WB_SIO_GPIO34_REG_INV4 0xe6
>> +
>> +#define WB_SIO_DEV_WDGPIO56 8
> 
>> +#define WB_SIO_WDGPIO56_REG_ENABLE 0x30
> 
> Why do we have duplication here?

Registers with offset >= 0x30 are
specific for a particular device.

That's a register in a different device
(which happen to have similar function as
register 0x30 in, for example, UARTC but
nothing in the datasheet guarantees that
such mapping will be universal).

>> +#define WB_SIO_WDGPIO56_ENABLE_6 2
>> +#define WB_SIO_WDGPIO56_ENABLE_5 1
> 
> Swap.

Ok.

> 
>> +#define WB_SIO_WDGPIO56_REG_IO5 0xe0
>> +#define WB_SIO_WDGPIO56_REG_DATA5 0xe1
>> +#define WB_SIO_WDGPIO56_REG_INV5 0xe2
>> +#define WB_SIO_WDGPIO56_REG_IO6 0xe4
>> +#define WB_SIO_WDGPIO56_REG_DATA6 0xe5
>> +#define WB_SIO_WDGPIO56_REG_INV6 0xe6
> 
> Duplication?

Again, it's a different device.

>> +
>> +#define WB_SIO_DEV_GPIO12 9
>> +#define WB_SIO_GPIO12_REG_ENABLE 0x30
>> +#define WB_SIO_GPIO12_ENABLE_2 1
>> +#define WB_SIO_GPIO12_ENABLE_1 0
>> +#define WB_SIO_GPIO12_REG_IO1 0xe0
>> +#define WB_SIO_GPIO12_REG_DATA1 0xe1
>> +#define WB_SIO_GPIO12_REG_INV1 0xe2
>> +#define WB_SIO_GPIO12_REG_IO2 0xe4
>> +#define WB_SIO_GPIO12_REG_DATA2 0xe5
>> +#define WB_SIO_GPIO12_REG_INV2 0xe6
>> +
>> +#define WB_SIO_DEV_UARTD 0xd
>> +#define WB_SIO_UARTD_REG_ENABLE 0x30
>> +#define WB_SIO_UARTD_ENABLE_ON 0
>> +
>> +#define WB_SIO_DEV_UARTE 0xe
>> +#define WB_SIO_UARTE_REG_ENABLE 0x30
>> +#define WB_SIO_UARTE_ENABLE_ON 0
>> +
>> +#define WB_SIO_REG_LOGICAL 7
>> +
>> +#define WB_SIO_REG_CHIP_MSB 0x20
>> +#define WB_SIO_REG_CHIP_LSB 0x21
>> +
>> +#define WB_SIO_REG_DPD 0x22
>> +#define WB_SIO_REG_DPD_UARTA 4
>> +#define WB_SIO_REG_DPD_UARTB 5
>> +
>> +#define WB_SIO_REG_IDPD 0x23
>> +#define WB_SIO_REG_IDPD_UARTF 7
>> +#define WB_SIO_REG_IDPD_UARTE 6
>> +#define WB_SIO_REG_IDPD_UARTD 5
>> +#define WB_SIO_REG_IDPD_UARTC 4
>> +
>> +#define WB_SIO_REG_GLOBAL_OPT 0x24
>> +#define WB_SIO_REG_GO_ENFDC 1
>> +
>> +#define WB_SIO_REG_OVTGPIO3456 0x29
>> +#define WB_SIO_REG_OG3456_G6PP 7
>> +#define WB_SIO_REG_OG3456_G5PP 5
>> +#define WB_SIO_REG_OG3456_G4PP 4
>> +#define WB_SIO_REG_OG3456_G3PP 3
>> +
>> +#define WB_SIO_REG_I2C_PS 0x2A
>> +#define WB_SIO_REG_I2CPS_I2CFS 1
>> +
>> +#define WB_SIO_REG_GPIO1_MF 0x2c
>> +#define WB_SIO_REG_G1MF_G2PP 7
>> +#define WB_SIO_REG_G1MF_G1PP 6
>> +#define WB_SIO_REG_G1MF_FS 3
>> +#define WB_SIO_REG_G1MF_FS_UARTB 3
>> +#define WB_SIO_REG_G1MF_FS_GPIO1 2
>> +#define WB_SIO_REG_G1MF_FS_IR 1
>> +#define WB_SIO_REG_G1MF_FS_IR_OFF 0
>> +
> 
>> +static u8 gpios;
>> +static u8 ppgpios;
>> +static u8 odgpios;
>> +static bool pledgpio;
>> +static bool beepgpio;
>> +static bool i2cgpio;
> 
> Hmm... Too many global variables.

All of them, besides i2cgpio, are module parameters, which require
global variables.

>> +
>> +static int winbond_sio_enter(u16 base)
>> +{
>> +	if (request_muxed_region(base, 2, WB_GPIO_DRIVER_NAME) ==
>> NULL) {
> 
> if (!request_...())

Ok.

>> +		pr_err(WB_GPIO_DRIVER_NAME ": cannot enter SIO at
>> address %x\n",
>> +		       (unsigned int)base);
> 
> %x, %hx, %hhx. No explicit casting.
> 
> Moreover, please, use dev_err() instead or drop this message completely.

Ok.

>> +		return -EBUSY;
> 
>> +	}
>> +
> 
>> +	outb(WB_SIO_EXT_ENTER_KEY, base);
>> +	outb(WB_SIO_EXT_ENTER_KEY, base);
> 
> Comment why double write is needed.

Ok.

>> +
>> +	return 0;
>> +}
>> +
>> +static void winbond_sio_select_logical(u16 base, u8 dev)
>> +{
>> +	outb(WB_SIO_REG_LOGICAL, base);
>> +	outb(dev, base + 1);
>> +}
>> +
>> +static void winbond_sio_leave(u16 base)
>> +{
>> +	outb(WB_SIO_EXT_EXIT_KEY, base);
>> +
>> +	release_region(base, 2);
>> +}
> 
>> +static void winbond_sio_reg_write(u16 base, u8 reg, u8 data)
>> +static u8 winbond_sio_reg_read(u16 base, u8 reg)
>> +static void winbond_sio_reg_bset(u16 base, u8 reg, u8 bit)
>> +static void winbond_sio_reg_bclear(u16 base, u8 reg, u8 bit)
>> +static bool winbond_sio_reg_btest(u16 base, u8 reg, u8 bit)
> 
> regmap API?

Looking at the regmap API:
* It does not support a I/O port space,

* It does not support a shared (muxed) register space, where one needs
to first request the space for a particular driver, then can perform
required sequence of operations, then should release the space,

* It does not support multiple logical devices sharing a register
address space where one needs first to select the logical device, then
perform the required sequence of operations.

>> +static const struct winbond_gpio_info winbond_gpio_infos[6] = {
> 
> Certainly candidate for regmap API.
> 
>> +	{ /* 5 */
>> +		.dev = WB_SIO_DEV_WDGPIO56,
>> +		.enablereg = WB_SIO_WDGPIO56_REG_ENABLE,
>> +		.enablebit = WB_SIO_WDGPIO56_ENABLE_6,
>> +		.outputreg = WB_SIO_REG_OVTGPIO3456,
>> +		.outputppbit = WB_SIO_REG_OG3456_G6PP,
>> +		.ioreg = WB_SIO_WDGPIO56_REG_IO6,
>> +		.invreg = WB_SIO_WDGPIO56_REG_INV6,
>> +		.datareg = WB_SIO_WDGPIO56_REG_DATA6,
>> +		.conflict = {
>> +			.name = "FDC",
>> +			.dev = WB_SIO_DEV_NONE,
>> +			.testreg = WB_SIO_REG_GLOBAL_OPT,
>> +			.testbit = WB_SIO_REG_GO_ENFDC,
>> +			.warnonly = false
>> +		}
>> +	}
>> +};
>> +
>> +/* returns whether changing a pin is allowed */
>> +static bool winbond_gpio_get_info(unsigned int gpio_num,
>> +				  const struct winbond_gpio_info
>> **info)
>> +{
>> +	bool allow_changing = true;
>> +	unsigned int i;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(winbond_gpio_infos); i++) {
>> +		if (!(gpios & BIT(i)))
>> +			continue;
> 
> for_each_set_bit()

Do we really want to replace a simple 6-iteration "for" loop with a
one that (possibly) does a function call at setup time then an another
per iteration?

>> +
>> +		if (gpio_num < 8)
>> +			break;
>> +
> 
>> +		gpio_num -= 8;
> 
> Yeah, consider to use % and / paired, see below.

Here it is only a simple subtraction of 8 lines per each set bit in
'gpios', how do you suggest to replace it with a faster
division-with-reminder operation (I guess it isn't supposed to be 
"if (gpio_num / 8 == 0) break;")?

>> +	}
>> +
>> +	/*
>> +	 * If for any reason we can't find this gpio number make sure
>> we
>> +	 * don't access the winbond_gpio_infos array beyond its
>> bounds.
>> +	 * Also, warn in this case, so we know something is seriously
>> wrong.
>> +	 */
>> +	if (WARN_ON(i >= ARRAY_SIZE(winbond_gpio_infos)))
>> +		i = 0;
> 
> Something is even more seriously wrong if you are going to mess with
> GPIO 0.
> 
> You have to return an error here.
> 
> Although it should not happen at all, AFAIU.

Yes, this condition should never happen in principle (it's only a
defensive programming check) so I think that printing a warning and
letting it read the first GPIO that is present while disallowing write
access would be fine in this very unlikely situation.

>> +
>> +	*info = &winbond_gpio_infos[i];
>> +
>> +	/*
>> +	 * GPIO2 (the second port) shares some pins with a basic PC
>> +	 * functionality, which is very likely controlled by the
>> firmware.
>> +	 * Don't allow changing these pins by default.
>> +	 */
>> +	if (i == 1) {
>> +		if (gpio_num == 0 && !pledgpio)
>> +			allow_changing = false;
>> +		else if (gpio_num == 1 && !beepgpio)
>> +			allow_changing = false;
>> +		else if ((gpio_num == 5 || gpio_num == 6) &&
>> !i2cgpio)
>> +			allow_changing = false;
> 
> Instead of allow_changing perhaps you need to use gpio_valid_mask
> (though it's not in upstream, yet? Linus?)

Can't find such identifier in the gpio tree (devel branch).

>> +	}
>> +
>> +	return allow_changing;
>> +}
> 
>> +static int winbond_gpio_direction_in(struct gpio_chip *gc,
>> +				     unsigned int gpio_num)
> 
> It's not gpio_num, it's offset. That is how we usually refer to that
> parameter in the drivers.

Ok, will change the parameter name.

>> +{
>> +	u16 *base = gpiochip_get_data(gc);
>> +	const struct winbond_gpio_info *info;
>> +	int ret;
>> +
>> +	if (!winbond_gpio_get_info(gpio_num, &info))
>> +		return -EACCES;
>> +
>> +	gpio_num %= 8;
> 
> Usually it goes paired with / 8 or alike.
> 
> Note, that
> % followed by / makes *one* assembly command on some architectures.
> 
> Same comments to the rest of similar functions.

I kind of understand what you had in mind, but I have a simpler solution:
I will simply return the reduced gpio number (or offset) from
winbond_gpio_get_info() function.
This way no division (or reminder) operation is necessary at all.

>> +
>> +	ret = winbond_sio_enter(*base);
>> +	if (ret)
>> +		return ret;
>> +
>> +	winbond_sio_select_logical(*base, info->dev);
>> +
>> +	winbond_sio_reg_bset(*base, info->ioreg, gpio_num);
>> +
>> +	winbond_sio_leave(*base);
>> +
>> +	return 0;
>> +}
>> +
>> +static int winbond_gpio_direction_out(struct gpio_chip *gc,
>> +				      unsigned int gpio_num,
>> +				      int val)
>> +{
>> +	u16 *base = gpiochip_get_data(gc);
> 
> out*() and in*() take unsigned long. So should this driver provide.

Ok, the port number will be changed unsigned long type.

>> +	return 0;
>> +}
>> +
>> +static void winbond_gpio_set(struct gpio_chip *gc, unsigned int
>> gpio_num,
>> +			     int val)
>> +{
>> +	u16 *base = gpiochip_get_data(gc);
>> +	const struct winbond_gpio_info *info;
>> +
>> +	if (!winbond_gpio_get_info(gpio_num, &info))
>> +		return;
>> +
>> +	gpio_num %= 8;
>> +
>> +	if (winbond_sio_enter(*base) != 0)
>> +		return;
>> +
>> +	winbond_sio_select_logical(*base, info->dev);
>> +
> 
>> +	if (winbond_sio_reg_btest(*base, info->invreg, gpio_num))
>> +		val = !val;
>> +
>> +	if (val)
> 
> if (val ^ winbond_sio_reg_btest()) ?

Ok.

>> +		winbond_sio_reg_bset(*base, info->datareg, gpio_num);
>> +	else
>> +		winbond_sio_reg_bclear(*base, info->datareg,
>> gpio_num);
> 
>> +}
>> +
>> +static struct gpio_chip winbond_gpio_chip = {
>> +	.base			= -1,
>> +	.label			= WB_GPIO_DRIVER_NAME,
> 
>> +	.owner			= THIS_MODULE,
> 
> 
> 
>> +	.can_sleep		= true,
>> +	.get			= winbond_gpio_get,
>> +	.direction_input	= winbond_gpio_direction_in,
>> +	.set			= winbond_gpio_set,
>> +	.direction_output	= winbond_gpio_direction_out,
>> +};
>> +
>> +static int winbond_gpio_probe(struct platform_device *pdev)
>> +{
>> +	u16 *base = dev_get_platdata(&pdev->dev);
>> +	unsigned int i;
>> +
>> +	if (base == NULL)
>> +		return -EINVAL;
>> +
>> +	/*
>> +	 * Add 8 gpios for every GPIO port that was enabled in gpios
>> +	 * module parameter (that wasn't disabled earlier in
>> +	 * winbond_gpio_configure() & co. due to, for example, a pin
>> conflict).
>> +	 */
>> +	winbond_gpio_chip.ngpio = 0;
> 
>> +	for (i = 0; i < 5; i++)
> 
> 5 is a magic.

Ok, will replace with ARRAY_SIZE as it is done in similar places.

>> +		if (gpios & BIT(i))
>> +			winbond_gpio_chip.ngpio += 8;
> 
> for_each_set_bit()

The same situation as with the for_each_set_bit() remark above.

>> +
>> +	if (gpios & BIT(5))
>> +		winbond_gpio_chip.ngpio += 5;
> 
> Comment needed for this one.

Ok.

>> +
>> +	winbond_gpio_chip.parent = &pdev->dev;
>> +
>> +	return devm_gpiochip_add_data(&pdev->dev, &winbond_gpio_chip,
>> base);
>> +}
>> +
>> +static void winbond_gpio_configure_port0_pins(u16 base)
>> +{
>> +	u8 val;
>> +
>> +	val = winbond_sio_reg_read(base, WB_SIO_REG_GPIO1_MF);
>> +	if ((val & WB_SIO_REG_G1MF_FS) == WB_SIO_REG_G1MF_FS_GPIO1)
>> +		return;
>> +
>> +	pr_warn(WB_GPIO_DRIVER_NAME
>> +		": GPIO1 pins were connected to something else
>> (%.2x), fixing\n",
>> +		(unsigned int)val);
>> +
>> +	val &= ~WB_SIO_REG_G1MF_FS;
>> +	val |= WB_SIO_REG_G1MF_FS_GPIO1;
>> +
>> +	winbond_sio_reg_write(base, WB_SIO_REG_GPIO1_MF, val);
>> +}
>> +
>> +static void winbond_gpio_configure_port1_check_i2c(u16 base)
>> +{
>> +	i2cgpio = !winbond_sio_reg_btest(base, WB_SIO_REG_I2C_PS,
>> +					 WB_SIO_REG_I2CPS_I2CFS);
>> +	if (!i2cgpio)
>> +		pr_warn(WB_GPIO_DRIVER_NAME
>> +			": disabling GPIO2.5 and GPIO2.6 as I2C is
>> enabled\n");
>> +}
>> +
>> +static bool winbond_gpio_configure_port(u16 base, unsigned int idx)
>> +{
>> +	const struct winbond_gpio_info *info =
>> &winbond_gpio_infos[idx];
>> +	const struct winbond_gpio_port_conflict *conflict = &info-
>>> conflict;
>> +
>> +	/* is there a possible conflicting device defined? */
>> +	if (conflict->name != NULL) {
>> +		if (conflict->dev != WB_SIO_DEV_NONE)
>> +			winbond_sio_select_logical(base, conflict-
>>> dev);
>> +
>> +		if (winbond_sio_reg_btest(base, conflict->testreg,
>> +					  conflict->testbit)) {
>> +			if (conflict->warnonly)
>> +				pr_warn(WB_GPIO_DRIVER_NAME
>> +					": enabled GPIO%u share pins
>> with active %s\n",
>> +					idx + 1, conflict->name);
>> +			else {
>> +				pr_warn(WB_GPIO_DRIVER_NAME
>> +					": disabling GPIO%u as %s is
>> enabled\n",
>> +					idx + 1, conflict->name);
>> +				return false;
>> +			}
>> +		}
>> +	}
>> +
>> +	/* GPIO1 and GPIO2 need some (additional) special handling */
>> +	if (idx == 0)
>> +		winbond_gpio_configure_port0_pins(base);
>> +	else if (idx == 1)
>> +		winbond_gpio_configure_port1_check_i2c(base);
>> +
>> +	winbond_sio_select_logical(base, info->dev);
>> +
>> +	winbond_sio_reg_bset(base, info->enablereg, info->enablebit);
>> +
>> +	if (ppgpios & BIT(idx))
>> +		winbond_sio_reg_bset(base, info->outputreg,
>> +				     info->outputppbit);
>> +	else if (odgpios & BIT(idx))
>> +		winbond_sio_reg_bclear(base, info->outputreg,
>> +				       info->outputppbit);
>> +	else
>> +		pr_notice(WB_GPIO_DRIVER_NAME ": GPIO%u pins are
>> %s\n", idx + 1,
>> +			  winbond_sio_reg_btest(base, info-
>>> outputreg,
>> +						info->outputppbit) ?
>> +			  "push-pull" :
>> +			  "open drain");
>> +
>> +	return true;
>> +}
>> +
>> +static int winbond_gpio_configure(u16 base)
>> +{
>> +	unsigned int i;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(winbond_gpio_infos); i++) {
>> +		if (!(gpios & BIT(i)))
>> +			continue;
>> +
>> +		if (!winbond_gpio_configure_port(base, i))
>> +			gpios &= ~BIT(i);
>> +	}
>> +
>> +	if (!(gpios & GENMASK(ARRAY_SIZE(winbond_gpio_infos) - 1,
>> 0))) {
>> +		pr_err(WB_GPIO_DRIVER_NAME
>> +		       ": please use 'gpios' module parameter to
>> select some active GPIO ports to enable\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static struct platform_device *winbond_gpio_pdev;
>> +
>> +/* probes chip at provided I/O base address, initializes and
>> registers it */
>> +static int winbond_gpio_try_probe_init(u16 base)
> 
> No.
> 
> Introduce 
> 
> struct winbond_sio_device {
>  struct device *dev;
>  unsigned long base;
> };
> 
> 
> Use it everywhere, including driver data.

This code is rewritten in the ISA bus version.

>> +{
>> +	u16 chip;
>> +	int ret;
>> +
>> +	ret = winbond_sio_enter(base);
>> +	if (ret)
>> +		return ret;
>> +
>> +	chip = winbond_sio_reg_read(base, WB_SIO_REG_CHIP_MSB) << 8;
>> +	chip |= winbond_sio_reg_read(base, WB_SIO_REG_CHIP_LSB);
>> +
>> +	pr_notice(WB_GPIO_DRIVER_NAME
>> +		  ": chip ID at %hx is %.4x\n",
>> +		  (unsigned int)base,
>> +		  (unsigned int)chip);
> 
> No explicit casting.
> 
> If you do such, you need to think twice what you *do wrong*.
> 
> There are really rare cases when it's needed.

Ok.

>> +
>> +	if ((chip & WB_SIO_CHIP_ID_W83627UHG_MASK) !=
>> +	    WB_SIO_CHIP_ID_W83627UHG) {
>> +		pr_err(WB_GPIO_DRIVER_NAME
>> +		       ": not an our chip\n");
>> +		winbond_sio_leave(base);
>> +		return -ENODEV;
>> +	}
>> +
>> +	ret = winbond_gpio_configure(base);
>> +
>> +	winbond_sio_leave(base);
>> +
>> +	if (ret)
>> +		return ret;
>> +
>> +	winbond_gpio_pdev =
>> platform_device_alloc(WB_GPIO_DRIVER_NAME, -1);
>> +	if (winbond_gpio_pdev == NULL)
>> +		return -ENOMEM;
>> +
>> +	ret = platform_device_add_data(winbond_gpio_pdev,
>> +				       &base, sizeof(base));
>> +	if (ret) {
>> +		pr_err(WB_GPIO_DRIVER_NAME
>> +		       ": cannot add platform data\n");
>> +		goto ret_put;
>> +	}
>> +
>> +	ret = platform_device_add(winbond_gpio_pdev);
>> +	if (ret) {
>> +		pr_err(WB_GPIO_DRIVER_NAME
>> +		       ": cannot add platform device\n");
>> +		goto ret_put;
>> +	}
>> +
>> +	return 0;
>> +
>> +ret_put:
>> +	platform_device_put(winbond_gpio_pdev);
> 
>> +	winbond_gpio_pdev = NULL;
> 
> ???

This code is rewritten in the ISA bus version.

>> +
>> +	return ret;
>> +}
>>
> 
>> +static int __init winbond_gpio_mod_init(void)
>> +{
>> +	int ret;
>> +
>> +	if (ppgpios & odgpios) {
>> +		pr_err(WB_GPIO_DRIVER_NAME
> 
> #define pr_fmt

Ok.
 
>> +			": some GPIO ports are set both to push-pull
>> and open drain mode at the same time\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	ret = platform_driver_register(&winbond_gpio_pdriver);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = winbond_gpio_try_probe_init(WB_SIO_BASE);
>> +	if (ret == -ENODEV || ret == -EBUSY)
>> +		ret = winbond_gpio_try_probe_init(WB_SIO_BASE_HIGH);
>> +	if (ret)
>> +		goto ret_unreg;
>> +
>> +	return 0;
>> +
>> +ret_unreg:
>> +	platform_driver_unregister(&winbond_gpio_pdriver);
>> +
>> +	return ret;
> 
> Oy vey, is it really right place to do this?

This code is rewritten in the ISA bus version.

>> +}
>> +
>> +static void __exit winbond_gpio_mod_exit(void)
>> +{
> 
>> +	platform_device_unregister(winbond_gpio_pdev);
>> +	platform_driver_unregister(&winbond_gpio_pdriver);
> 
> Hmm... what?

This code is rewritten in the ISA bus version.
 
>> +}
>> +
>> +module_init(winbond_gpio_mod_init);
>> +module_exit(winbond_gpio_mod_exit);
>>
> 
>> +MODULE_AUTHOR("Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>");
>> +MODULE_DESCRIPTION("GPIO interface for Winbond Super I/O chips");
> 
>> +MODULE_LICENSE("GPL");
> 
> Does it match SPDX identifier?
> 

Yes, since according to MODULE_LICENSE() macro comment "GPL" means "GNU
Public License v2 or later".

Maciej
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