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Sender: Guenter Roeck <groeck7@gmail.com>
Message-ID: <17636709-e536-b8c5-cb8f-976ac7657735@roeck-us.net>
Date:   Fri, 13 May 2022 14:47:58 -0700
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To:     Henning Schild <henning.schild@siemens.com>,
        linux-kernel@vger.kernel.org, linux-leds@vger.kernel.org,
        platform-driver-x86@vger.kernel.org, linux-watchdog@vger.kernel.org
Cc:     Srikanth Krishnakar <skrishnakar@gmail.com>,
        Jan Kiszka <jan.kiszka@siemens.com>,
        Gerd Haeussler <gerd.haeussler.ext@siemens.com>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Mark Gross <mgross@linux.intel.com>,
        Hans de Goede <hdegoede@redhat.com>,
        Pavel Machek <pavel@ucw.cz>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        Enrico Weigelt <lkml@metux.net>
References: <20211213120502.20661-1-henning.schild@siemens.com>
 <20211213120502.20661-3-henning.schild@siemens.com>
 <20220513214030.7254b1bf@md1za8fc.ad001.siemens.net>
From:   Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH v5 2/4] leds: simatic-ipc-leds: add new driver for Siemens
 Industial PCs
In-Reply-To: <20220513214030.7254b1bf@md1za8fc.ad001.siemens.net>
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On 5/13/22 12:40, Henning Schild wrote:
> Am Mon, 13 Dec 2021 13:05:00 +0100
> schrieb Henning Schild <henning.schild@siemens.com>:
> 
>> This driver adds initial support for several devices from Siemens. It
>> is based on a platform driver introduced in an earlier commit.
>>
>> One of the supported machines has GPIO connected LEDs, here we poke
>> GPIO memory directly because pinctrl does not come up.
>>
>> Signed-off-by: Henning Schild <henning.schild@siemens.com>
>> ---
>>   drivers/leds/Kconfig                   |   3 +
>>   drivers/leds/Makefile                  |   3 +
>>   drivers/leds/simple/Kconfig            |  11 ++
>>   drivers/leds/simple/Makefile           |   2 +
>>   drivers/leds/simple/simatic-ipc-leds.c | 202
>> +++++++++++++++++++++++++ 5 files changed, 221 insertions(+)
>>   create mode 100644 drivers/leds/simple/Kconfig
>>   create mode 100644 drivers/leds/simple/Makefile
>>   create mode 100644 drivers/leds/simple/simatic-ipc-leds.c
>>
>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>> index ed800f5da7d8..ac6688d7a3f4 100644
>> --- a/drivers/leds/Kconfig
>> +++ b/drivers/leds/Kconfig
>> @@ -879,4 +879,7 @@ source "drivers/leds/flash/Kconfig"
>>   comment "LED Triggers"
>>   source "drivers/leds/trigger/Kconfig"
>>   
>> +comment "Simple LED drivers"
>> +source "drivers/leds/simple/Kconfig"
>> +
>>   endif # NEW_LEDS
>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>> index c636ec069612..1a719caf14c0 100644
>> --- a/drivers/leds/Makefile
>> +++ b/drivers/leds/Makefile
>> @@ -105,3 +105,6 @@ obj-$(CONFIG_LEDS_TRIGGERS)		+=
>> trigger/
>>   # LED Blink
>>   obj-y					+= blink/
>> +
>> +# Simple LED drivers
>> +obj-y					+= simple/
>> diff --git a/drivers/leds/simple/Kconfig b/drivers/leds/simple/Kconfig
>> new file mode 100644
>> index 000000000000..9f6a68336659
>> --- /dev/null
>> +++ b/drivers/leds/simple/Kconfig
>> @@ -0,0 +1,11 @@
>> +# SPDX-License-Identifier: GPL-2.0-only
>> +config LEDS_SIEMENS_SIMATIC_IPC
>> +	tristate "LED driver for Siemens Simatic IPCs"
>> +	depends on LEDS_CLASS
>> +	depends on SIEMENS_SIMATIC_IPC
> 
> Trying to bring this into distros i think this one should rather be
> "select SIEMENS_SIMATIC_IPC" and the same thought goes for wdt.
> 
> Users care about enabling a feature and maybe not too much about having
> to enable infra, enabling SIEMENS_SIMATIC_IPC is just infra and useless
> without LEDS_SIEMENS_SIMATIC_IPC and/or SIEMENS_SIMATIC_IPC_WDT.
> 
> So those two should probably "select" and not "depend".
> 
> I will send a patch, feel free to tell me that i am wrong and teach me
> about how deps should work.
> 

I disagree. Normally drivers depend on the platform and don't select it.
It would make more sense to specify something like

	depends on SIEMENS_SIMATIC_IPC
	default SIEMENS_SIMATIC_IPC

In this context, the description for SIEMENS_SIMATIC_IPC is
a bit misleading. Something like "Platform driver for Simatic
Industrial PC" or just "Support for Simatic Industrial PC"
would be a better description.

Guenter

> regards,
> Henning
> 
>> +	help
>> +	  This option enables support for the LEDs of several
>> Industrial PCs
>> +	  from Siemens.
>> +
>> +	  To compile this driver as a module, choose M here: the
>> module
>> +	  will be called simatic-ipc-leds.
>> diff --git a/drivers/leds/simple/Makefile
>> b/drivers/leds/simple/Makefile new file mode 100644
>> index 000000000000..8481f1e9e360
>> --- /dev/null
>> +++ b/drivers/leds/simple/Makefile
>> @@ -0,0 +1,2 @@
>> +# SPDX-License-Identifier: GPL-2.0
>> +obj-$(CONFIG_LEDS_SIEMENS_SIMATIC_IPC)	+= simatic-ipc-leds.o
>> diff --git a/drivers/leds/simple/simatic-ipc-leds.c
>> b/drivers/leds/simple/simatic-ipc-leds.c new file mode 100644
>> index 000000000000..ff2c96e73241
>> --- /dev/null
>> +++ b/drivers/leds/simple/simatic-ipc-leds.c
>> @@ -0,0 +1,202 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Siemens SIMATIC IPC driver for LEDs
>> + *
>> + * Copyright (c) Siemens AG, 2018-2021
>> + *
>> + * Authors:
>> + *  Henning Schild <henning.schild@siemens.com>
>> + *  Jan Kiszka <jan.kiszka@siemens.com>
>> + *  Gerd Haeussler <gerd.haeussler.ext@siemens.com>
>> + */
>> +
>> +#include <linux/ioport.h>
>> +#include <linux/kernel.h>
>> +#include <linux/leds.h>
>> +#include <linux/module.h>
>> +#include <linux/pci.h>
>> +#include <linux/platform_data/x86/simatic-ipc-base.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/sizes.h>
>> +#include <linux/spinlock.h>
>> +
>> +#define SIMATIC_IPC_LED_PORT_BASE	0x404E
>> +
>> +struct simatic_ipc_led {
>> +	unsigned int value; /* mask for io and offset for mem */
>> +	char *name;
>> +	struct led_classdev cdev;
>> +};
>> +
>> +static struct simatic_ipc_led simatic_ipc_leds_io[] = {
>> +	{1 << 15, "green:" LED_FUNCTION_STATUS "-1" },
>> +	{1 << 7,  "yellow:" LED_FUNCTION_STATUS "-1" },
>> +	{1 << 14, "red:" LED_FUNCTION_STATUS "-2" },
>> +	{1 << 6,  "yellow:" LED_FUNCTION_STATUS "-2" },
>> +	{1 << 13, "red:" LED_FUNCTION_STATUS "-3" },
>> +	{1 << 5,  "yellow:" LED_FUNCTION_STATUS "-3" },
>> +	{ }
>> +};
>> +
>> +/* the actual start will be discovered with PCI, 0 is a placeholder
>> */ +struct resource simatic_ipc_led_mem_res = DEFINE_RES_MEM_NAMED(0,
>> SZ_4K, KBUILD_MODNAME); +
>> +static void *simatic_ipc_led_memory;
>> +
>> +static struct simatic_ipc_led simatic_ipc_leds_mem[] = {
>> +	{0x500 + 0x1A0, "red:" LED_FUNCTION_STATUS "-1"},
>> +	{0x500 + 0x1A8, "green:" LED_FUNCTION_STATUS "-1"},
>> +	{0x500 + 0x1C8, "red:" LED_FUNCTION_STATUS "-2"},
>> +	{0x500 + 0x1D0, "green:" LED_FUNCTION_STATUS "-2"},
>> +	{0x500 + 0x1E0, "red:" LED_FUNCTION_STATUS "-3"},
>> +	{0x500 + 0x198, "green:" LED_FUNCTION_STATUS "-3"},
>> +	{ }
>> +};
>> +
>> +static struct resource simatic_ipc_led_io_res =
>> +	DEFINE_RES_IO_NAMED(SIMATIC_IPC_LED_PORT_BASE, SZ_2,
>> KBUILD_MODNAME); +
>> +static DEFINE_SPINLOCK(reg_lock);
>> +
>> +static inline struct simatic_ipc_led *cdev_to_led(struct
>> led_classdev *led_cd) +{
>> +	return container_of(led_cd, struct simatic_ipc_led, cdev);
>> +}
>> +
>> +static void simatic_ipc_led_set_io(struct led_classdev *led_cd,
>> +				   enum led_brightness brightness)
>> +{
>> +	struct simatic_ipc_led *led = cdev_to_led(led_cd);
>> +	unsigned long flags;
>> +	unsigned int val;
>> +
>> +	spin_lock_irqsave(&reg_lock, flags);
>> +
>> +	val = inw(SIMATIC_IPC_LED_PORT_BASE);
>> +	if (brightness == LED_OFF)
>> +		outw(val | led->value, SIMATIC_IPC_LED_PORT_BASE);
>> +	else
>> +		outw(val & ~led->value, SIMATIC_IPC_LED_PORT_BASE);
>> +
>> +	spin_unlock_irqrestore(&reg_lock, flags);
>> +}
>> +
>> +static enum led_brightness simatic_ipc_led_get_io(struct
>> led_classdev *led_cd) +{
>> +	struct simatic_ipc_led *led = cdev_to_led(led_cd);
>> +
>> +	return inw(SIMATIC_IPC_LED_PORT_BASE) & led->value ? LED_OFF
>> : led_cd->max_brightness; +}
>> +
>> +static void simatic_ipc_led_set_mem(struct led_classdev *led_cd,
>> +				    enum led_brightness brightness)
>> +{
>> +	struct simatic_ipc_led *led = cdev_to_led(led_cd);
>> +
>> +	u32 *p;
>> +
>> +	p = simatic_ipc_led_memory + led->value;
>> +	*p = (*p & ~1) | (brightness == LED_OFF);
>> +}
>> +
>> +static enum led_brightness simatic_ipc_led_get_mem(struct
>> led_classdev *led_cd) +{
>> +	struct simatic_ipc_led *led = cdev_to_led(led_cd);
>> +
>> +	u32 *p;
>> +
>> +	p = simatic_ipc_led_memory + led->value;
>> +	return (*p & 1) ? LED_OFF : led_cd->max_brightness;
>> +}
>> +
>> +static int simatic_ipc_leds_probe(struct platform_device *pdev)
>> +{
>> +	const struct simatic_ipc_platform *plat =
>> pdev->dev.platform_data;
>> +	struct device *dev = &pdev->dev;
>> +	struct simatic_ipc_led *ipcled;
>> +	struct led_classdev *cdev;
>> +	struct resource *res;
>> +	int err, type;
>> +	u32 *p;
>> +
>> +	switch (plat->devmode) {
>> +	case SIMATIC_IPC_DEVICE_227D:
>> +	case SIMATIC_IPC_DEVICE_427E:
>> +		res = &simatic_ipc_led_io_res;
>> +		ipcled = simatic_ipc_leds_io;
>> +		/* on 227D the two bytes work the other way araound
>> */
>> +		if (plat->devmode == SIMATIC_IPC_DEVICE_227D) {
>> +			while (ipcled->value) {
>> +				ipcled->value =
>> swab16(ipcled->value);
>> +				ipcled++;
>> +			}
>> +			ipcled = simatic_ipc_leds_io;
>> +		}
>> +		type = IORESOURCE_IO;
>> +		if (!devm_request_region(dev, res->start,
>> resource_size(res), KBUILD_MODNAME)) {
>> +			dev_err(dev, "Unable to register IO resource
>> at %pR\n", res);
>> +			return -EBUSY;
>> +		}
>> +		break;
>> +	case SIMATIC_IPC_DEVICE_127E:
>> +		res = &simatic_ipc_led_mem_res;
>> +		ipcled = simatic_ipc_leds_mem;
>> +		type = IORESOURCE_MEM;
>> +
>> +		/* get GPIO base from PCI */
>> +		res->start = simatic_ipc_get_membase0(PCI_DEVFN(13,
>> 0));
>> +		if (res->start == 0)
>> +			return -ENODEV;
>> +
>> +		/* do the final address calculation */
>> +		res->start = res->start + (0xC5 << 16);
>> +		res->end += res->start;
>> +
>> +		simatic_ipc_led_memory = devm_ioremap_resource(dev,
>> res);
>> +		if (IS_ERR(simatic_ipc_led_memory))
>> +			return PTR_ERR(simatic_ipc_led_memory);
>> +
>> +		/* initialize power/watchdog LED */
>> +		p = simatic_ipc_led_memory + 0x500 + 0x1D8; /*
>> PM_WDT_OUT */
>> +		*p = (*p & ~1);
>> +		p = simatic_ipc_led_memory + 0x500 + 0x1C0; /*
>> PM_BIOS_BOOT_N */
>> +		*p = (*p | 1);
>> +
>> +		break;
>> +	default:
>> +		return -ENODEV;
>> +	}
>> +
>> +	while (ipcled->value) {
>> +		cdev = &ipcled->cdev;
>> +		if (type == IORESOURCE_MEM) {
>> +			cdev->brightness_set =
>> simatic_ipc_led_set_mem;
>> +			cdev->brightness_get =
>> simatic_ipc_led_get_mem;
>> +		} else {
>> +			cdev->brightness_set =
>> simatic_ipc_led_set_io;
>> +			cdev->brightness_get =
>> simatic_ipc_led_get_io;
>> +		}
>> +		cdev->max_brightness = LED_ON;
>> +		cdev->name = ipcled->name;
>> +
>> +		err = devm_led_classdev_register(dev, cdev);
>> +		if (err < 0)
>> +			return err;
>> +		ipcled++;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static struct platform_driver simatic_ipc_led_driver = {
>> +	.probe = simatic_ipc_leds_probe,
>> +	.driver = {
>> +		.name = KBUILD_MODNAME,
>> +	}
>> +};
>> +
>> +module_platform_driver(simatic_ipc_led_driver);
>> +
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_ALIAS("platform:" KBUILD_MODNAME);
>> +MODULE_AUTHOR("Henning Schild <henning.schild@siemens.com>");
>