diff mbox series

[v6,5/7] leds: simatic-ipc-leds-gpio: add new model 227G

Message ID 20220825104422.14156-6-henning.schild@siemens.com
State New
Headers show
Series add support for another simatic board | expand

Commit Message

Henning Schild Aug. 25, 2022, 10:44 a.m. UTC
This adds support of the Siemens Simatic IPC227G. Its LEDs are connected
to GPIO pins provided by the gpio-f7188x module. We make sure that
gets loaded, if not enabled in the kernel config no LED support will be
available.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Henning Schild <henning.schild@siemens.com>
---
 drivers/leds/simple/simatic-ipc-leds-gpio.c   | 42 ++++++++++++++++---
 drivers/platform/x86/simatic-ipc.c            |  4 +-
 .../platform_data/x86/simatic-ipc-base.h      |  1 +
 include/linux/platform_data/x86/simatic-ipc.h |  1 +
 4 files changed, 42 insertions(+), 6 deletions(-)

Comments

Henning Schild Aug. 25, 2022, 5:33 p.m. UTC | #1
Am Thu, 25 Aug 2022 12:44:20 +0200
schrieb Henning Schild <henning.schild@siemens.com>:

> This adds support of the Siemens Simatic IPC227G. Its LEDs are
> connected to GPIO pins provided by the gpio-f7188x module. We make
> sure that gets loaded, if not enabled in the kernel config no LED
> support will be available.
> 
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Reviewed-by: Hans de Goede <hdegoede@redhat.com>
> Signed-off-by: Henning Schild <henning.schild@siemens.com>
> ---
>  drivers/leds/simple/simatic-ipc-leds-gpio.c   | 42
> ++++++++++++++++--- drivers/platform/x86/simatic-ipc.c            |
> 4 +- .../platform_data/x86/simatic-ipc-base.h      |  1 +
>  include/linux/platform_data/x86/simatic-ipc.h |  1 +
>  4 files changed, 42 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/leds/simple/simatic-ipc-leds-gpio.c
> b/drivers/leds/simple/simatic-ipc-leds-gpio.c index
> 4c9e663a90ba..0d73dcbeec2d 100644 ---
> a/drivers/leds/simple/simatic-ipc-leds-gpio.c +++
> b/drivers/leds/simple/simatic-ipc-leds-gpio.c @@ -13,28 +13,45 @@
>  #include <linux/leds.h>
>  #include <linux/module.h>
>  #include <linux/platform_device.h>
> +#include <linux/platform_data/x86/simatic-ipc-base.h>
>  
> -static struct gpiod_lookup_table simatic_ipc_led_gpio_table = {
> +struct gpiod_lookup_table *simatic_ipc_led_gpio_table;
> +
> +static struct gpiod_lookup_table simatic_ipc_led_gpio_table_127e = {
>  	.dev_id = "leds-gpio",
>  	.table = {
> -		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 51, NULL, 0,
> GPIO_ACTIVE_LOW), GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 52, NULL,
> 1, GPIO_ACTIVE_LOW), GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 53,
> NULL, 2, GPIO_ACTIVE_LOW), GPIO_LOOKUP_IDX("apollolake-pinctrl.0",
> 57, NULL, 3, GPIO_ACTIVE_LOW),
> GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 58, NULL, 4,
> GPIO_ACTIVE_LOW), GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 60, NULL,
> 5, GPIO_ACTIVE_LOW),
> +		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 51, NULL, 0,
> GPIO_ACTIVE_LOW), GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 56, NULL,
> 6, GPIO_ACTIVE_LOW), GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 59,
> NULL, 7, GPIO_ACTIVE_HIGH), },
>  };
>  
> +static struct gpiod_lookup_table simatic_ipc_led_gpio_table_227g = {
> +	.dev_id = "leds-gpio",
> +	.table = {
> +		GPIO_LOOKUP_IDX("gpio-f7188x-2", 0, NULL, 0,
> GPIO_ACTIVE_LOW),
> +		GPIO_LOOKUP_IDX("gpio-f7188x-2", 1, NULL, 1,
> GPIO_ACTIVE_LOW),
> +		GPIO_LOOKUP_IDX("gpio-f7188x-2", 2, NULL, 2,
> GPIO_ACTIVE_LOW),
> +		GPIO_LOOKUP_IDX("gpio-f7188x-2", 3, NULL, 3,
> GPIO_ACTIVE_LOW),
> +		GPIO_LOOKUP_IDX("gpio-f7188x-2", 4, NULL, 4,
> GPIO_ACTIVE_LOW),
> +		GPIO_LOOKUP_IDX("gpio-f7188x-2", 5, NULL, 5,
> GPIO_ACTIVE_LOW),
> +		GPIO_LOOKUP_IDX("gpio-f7188x-3", 6, NULL, 6,
> GPIO_ACTIVE_HIGH),
> +		GPIO_LOOKUP_IDX("gpio-f7188x-3", 7, NULL, 7,
> GPIO_ACTIVE_HIGH),
> +	}
> +};
> +
>  static const struct gpio_led simatic_ipc_gpio_leds[] = {
> -	{ .name = "green:" LED_FUNCTION_STATUS "-3" },
>  	{ .name = "red:" LED_FUNCTION_STATUS "-1" },
>  	{ .name = "green:" LED_FUNCTION_STATUS "-1" },
>  	{ .name = "red:" LED_FUNCTION_STATUS "-2" },
>  	{ .name = "green:" LED_FUNCTION_STATUS "-2" },
>  	{ .name = "red:" LED_FUNCTION_STATUS "-3" },
> +	{ .name = "green:" LED_FUNCTION_STATUS "-3" },
>  };

Concerning these two tables from above i have a question i need to find
an answer for for maintaining the out-of-tree modules of these drivers.

When getting the drivers into the kernel i had to rename the leds but
in out-of-tree i would like to keep the old names and just equip their
setters/getters with a deprecation warning. Just to give existing
users time to slowly adopt the upstream name change if i can.

In the open-coded way i just defined each LED twice and added a strcmp
+ pr_warn. With the "leds-gpio" version i still fail to find a solution
which does not get me into -EBUSY. So i already fail at the second
definition of the legacy name, not even had a chance to think about how
to smuggle in my deprecation warning.

I know out-of-tree is not a concern to people here, but someone might
have an answer anyhow.

Thanks,
Henning

>  static const struct gpio_led_platform_data
> simatic_ipc_gpio_leds_pdata = { @@ -46,7 +63,7 @@ static struct
> platform_device *simatic_leds_pdev; 
>  static int simatic_ipc_leds_gpio_remove(struct platform_device *pdev)
>  {
> -	gpiod_remove_lookup_table(&simatic_ipc_led_gpio_table);
> +	gpiod_remove_lookup_table(simatic_ipc_led_gpio_table);
>  	platform_device_unregister(simatic_leds_pdev);
>  
>  	return 0;
> @@ -54,10 +71,25 @@ static int simatic_ipc_leds_gpio_remove(struct
> platform_device *pdev) 
>  static int simatic_ipc_leds_gpio_probe(struct platform_device *pdev)
>  {
> +	const struct simatic_ipc_platform *plat =
> pdev->dev.platform_data; struct gpio_desc *gpiod;
>  	int err;
>  
> -	gpiod_add_lookup_table(&simatic_ipc_led_gpio_table);
> +	switch (plat->devmode) {
> +	case SIMATIC_IPC_DEVICE_127E:
> +		simatic_ipc_led_gpio_table =
> &simatic_ipc_led_gpio_table_127e;
> +		break;
> +	case SIMATIC_IPC_DEVICE_227G:
> +		if (!IS_ENABLED(CONFIG_GPIO_F7188X))
> +			return -ENODEV;
> +		request_module("gpio-f7188x");
> +		simatic_ipc_led_gpio_table =
> &simatic_ipc_led_gpio_table_227g;
> +		break;
> +	default:
> +		return -ENODEV;
> +	}
> +
> +	gpiod_add_lookup_table(simatic_ipc_led_gpio_table);
>  	simatic_leds_pdev = platform_device_register_resndata(NULL,
>  		"leds-gpio", PLATFORM_DEVID_NONE, NULL, 0,
>  		&simatic_ipc_gpio_leds_pdata,
> diff --git a/drivers/platform/x86/simatic-ipc.c
> b/drivers/platform/x86/simatic-ipc.c index ca3647b751d5..1825ef21a86d
> 100644 --- a/drivers/platform/x86/simatic-ipc.c
> +++ b/drivers/platform/x86/simatic-ipc.c
> @@ -41,6 +41,7 @@ static struct {
>  	{SIMATIC_IPC_IPC127E, SIMATIC_IPC_DEVICE_127E,
> SIMATIC_IPC_DEVICE_NONE}, {SIMATIC_IPC_IPC227D,
> SIMATIC_IPC_DEVICE_227D, SIMATIC_IPC_DEVICE_NONE},
> {SIMATIC_IPC_IPC227E, SIMATIC_IPC_DEVICE_427E,
> SIMATIC_IPC_DEVICE_227E},
> +	{SIMATIC_IPC_IPC227G, SIMATIC_IPC_DEVICE_227G,
> SIMATIC_IPC_DEVICE_NONE}, {SIMATIC_IPC_IPC277E,
> SIMATIC_IPC_DEVICE_NONE, SIMATIC_IPC_DEVICE_227E},
> {SIMATIC_IPC_IPC427D, SIMATIC_IPC_DEVICE_427E,
> SIMATIC_IPC_DEVICE_NONE}, {SIMATIC_IPC_IPC427E,
> SIMATIC_IPC_DEVICE_427E, SIMATIC_IPC_DEVICE_427E}, @@ -65,7 +66,8 @@
> static int register_platform_devices(u32 station_id) } 
>  	if (ledmode != SIMATIC_IPC_DEVICE_NONE) {
> -		if (ledmode == SIMATIC_IPC_DEVICE_127E)
> +		if (ledmode == SIMATIC_IPC_DEVICE_127E ||
> +		    ledmode == SIMATIC_IPC_DEVICE_227G)
>  			pdevname = KBUILD_MODNAME "_leds_gpio";
>  		platform_data.devmode = ledmode;
>  		ipc_led_platform_device =
> diff --git a/include/linux/platform_data/x86/simatic-ipc-base.h
> b/include/linux/platform_data/x86/simatic-ipc-base.h index
> 39fefd48cf4d..57d6a10dfc9e 100644 ---
> a/include/linux/platform_data/x86/simatic-ipc-base.h +++
> b/include/linux/platform_data/x86/simatic-ipc-base.h @@ -19,6 +19,7 @@
>  #define SIMATIC_IPC_DEVICE_427E 2
>  #define SIMATIC_IPC_DEVICE_127E 3
>  #define SIMATIC_IPC_DEVICE_227E 4
> +#define SIMATIC_IPC_DEVICE_227G 5
>  
>  struct simatic_ipc_platform {
>  	u8	devmode;
> diff --git a/include/linux/platform_data/x86/simatic-ipc.h
> b/include/linux/platform_data/x86/simatic-ipc.h index
> f3b76b39776b..7a2e79f3be0b 100644 ---
> a/include/linux/platform_data/x86/simatic-ipc.h +++
> b/include/linux/platform_data/x86/simatic-ipc.h @@ -31,6 +31,7 @@
> enum simatic_ipc_station_ids { SIMATIC_IPC_IPC427E = 0x00000A01,
>  	SIMATIC_IPC_IPC477E = 0x00000A02,
>  	SIMATIC_IPC_IPC127E = 0x00000D01,
> +	SIMATIC_IPC_IPC227G = 0x00000F01,
>  };
>  
>  static inline u32 simatic_ipc_get_station_id(u8 *data, int max_len)
Andy Shevchenko Aug. 25, 2022, 6:03 p.m. UTC | #2
On Thu, Aug 25, 2022 at 8:51 PM Henning Schild
<henning.schild@siemens.com> wrote:
> Am Thu, 25 Aug 2022 12:44:20 +0200
> schrieb Henning Schild <henning.schild@siemens.com>:

...

> Concerning these two tables from above i have a question i need to find
> an answer for for maintaining the out-of-tree modules of these drivers.
>
> When getting the drivers into the kernel i had to rename the leds but
> in out-of-tree i would like to keep the old names and just equip their
> setters/getters with a deprecation warning. Just to give existing
> users time to slowly adopt the upstream name change if i can.
>
> In the open-coded way i just defined each LED twice and added a strcmp
> + pr_warn. With the "leds-gpio" version i still fail to find a solution
> which does not get me into -EBUSY. So i already fail at the second
> definition of the legacy name, not even had a chance to think about how
> to smuggle in my deprecation warning.
>
> I know out-of-tree is not a concern to people here, but someone might
> have an answer anyhow.

Yes, we (upstream) don't care about out-of-tree stuff. But I think
what you are asking for is kinda an alias. Maybe you simply can create
a module that will wait for the led appearing (by notify that adds a
device or alike) and create an alias by sysfs symlink (IIRC there are
kernel APIs for that)? It will be another out-of-tree module that you
may drop whenever is time.
Henning Schild Aug. 25, 2022, 6:27 p.m. UTC | #3
Am Thu, 25 Aug 2022 21:03:53 +0300
schrieb Andy Shevchenko <andy.shevchenko@gmail.com>:

> On Thu, Aug 25, 2022 at 8:51 PM Henning Schild
> <henning.schild@siemens.com> wrote:
> > Am Thu, 25 Aug 2022 12:44:20 +0200
> > schrieb Henning Schild <henning.schild@siemens.com>:  
> 
> ...
> 
> > Concerning these two tables from above i have a question i need to
> > find an answer for for maintaining the out-of-tree modules of these
> > drivers.
> >
> > When getting the drivers into the kernel i had to rename the leds
> > but in out-of-tree i would like to keep the old names and just
> > equip their setters/getters with a deprecation warning. Just to
> > give existing users time to slowly adopt the upstream name change
> > if i can.
> >
> > In the open-coded way i just defined each LED twice and added a
> > strcmp
> > + pr_warn. With the "leds-gpio" version i still fail to find a
> > solution which does not get me into -EBUSY. So i already fail at
> > the second definition of the legacy name, not even had a chance to
> > think about how to smuggle in my deprecation warning.
> >
> > I know out-of-tree is not a concern to people here, but someone
> > might have an answer anyhow.  
> 
> Yes, we (upstream) don't care about out-of-tree stuff. But I think
> what you are asking for is kinda an alias. Maybe you simply can create
> a module that will wait for the led appearing (by notify that adds a
> device or alike) and create an alias by sysfs symlink (IIRC there are
> kernel APIs for that)? It will be another out-of-tree module that you
> may drop whenever is time.

Thanks! That sounds like a very good idea indeed. Would also keep the
code free of #ifdef and reduce the maint effort for the out-of-tree. I
was trying udev earlier but failed. Will give such a symlink driver a
try.
Might be hard to get the deprecation warning into each access, but will
have to resort to probe-time instead of access-time.

regards,
Henning
diff mbox series

Patch

diff --git a/drivers/leds/simple/simatic-ipc-leds-gpio.c b/drivers/leds/simple/simatic-ipc-leds-gpio.c
index 4c9e663a90ba..0d73dcbeec2d 100644
--- a/drivers/leds/simple/simatic-ipc-leds-gpio.c
+++ b/drivers/leds/simple/simatic-ipc-leds-gpio.c
@@ -13,28 +13,45 @@ 
 #include <linux/leds.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/platform_data/x86/simatic-ipc-base.h>
 
-static struct gpiod_lookup_table simatic_ipc_led_gpio_table = {
+struct gpiod_lookup_table *simatic_ipc_led_gpio_table;
+
+static struct gpiod_lookup_table simatic_ipc_led_gpio_table_127e = {
 	.dev_id = "leds-gpio",
 	.table = {
-		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 51, NULL, 0, GPIO_ACTIVE_LOW),
 		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 52, NULL, 1, GPIO_ACTIVE_LOW),
 		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 53, NULL, 2, GPIO_ACTIVE_LOW),
 		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 57, NULL, 3, GPIO_ACTIVE_LOW),
 		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 58, NULL, 4, GPIO_ACTIVE_LOW),
 		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 60, NULL, 5, GPIO_ACTIVE_LOW),
+		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 51, NULL, 0, GPIO_ACTIVE_LOW),
 		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 56, NULL, 6, GPIO_ACTIVE_LOW),
 		GPIO_LOOKUP_IDX("apollolake-pinctrl.0", 59, NULL, 7, GPIO_ACTIVE_HIGH),
 	},
 };
 
+static struct gpiod_lookup_table simatic_ipc_led_gpio_table_227g = {
+	.dev_id = "leds-gpio",
+	.table = {
+		GPIO_LOOKUP_IDX("gpio-f7188x-2", 0, NULL, 0, GPIO_ACTIVE_LOW),
+		GPIO_LOOKUP_IDX("gpio-f7188x-2", 1, NULL, 1, GPIO_ACTIVE_LOW),
+		GPIO_LOOKUP_IDX("gpio-f7188x-2", 2, NULL, 2, GPIO_ACTIVE_LOW),
+		GPIO_LOOKUP_IDX("gpio-f7188x-2", 3, NULL, 3, GPIO_ACTIVE_LOW),
+		GPIO_LOOKUP_IDX("gpio-f7188x-2", 4, NULL, 4, GPIO_ACTIVE_LOW),
+		GPIO_LOOKUP_IDX("gpio-f7188x-2", 5, NULL, 5, GPIO_ACTIVE_LOW),
+		GPIO_LOOKUP_IDX("gpio-f7188x-3", 6, NULL, 6, GPIO_ACTIVE_HIGH),
+		GPIO_LOOKUP_IDX("gpio-f7188x-3", 7, NULL, 7, GPIO_ACTIVE_HIGH),
+	}
+};
+
 static const struct gpio_led simatic_ipc_gpio_leds[] = {
-	{ .name = "green:" LED_FUNCTION_STATUS "-3" },
 	{ .name = "red:" LED_FUNCTION_STATUS "-1" },
 	{ .name = "green:" LED_FUNCTION_STATUS "-1" },
 	{ .name = "red:" LED_FUNCTION_STATUS "-2" },
 	{ .name = "green:" LED_FUNCTION_STATUS "-2" },
 	{ .name = "red:" LED_FUNCTION_STATUS "-3" },
+	{ .name = "green:" LED_FUNCTION_STATUS "-3" },
 };
 
 static const struct gpio_led_platform_data simatic_ipc_gpio_leds_pdata = {
@@ -46,7 +63,7 @@  static struct platform_device *simatic_leds_pdev;
 
 static int simatic_ipc_leds_gpio_remove(struct platform_device *pdev)
 {
-	gpiod_remove_lookup_table(&simatic_ipc_led_gpio_table);
+	gpiod_remove_lookup_table(simatic_ipc_led_gpio_table);
 	platform_device_unregister(simatic_leds_pdev);
 
 	return 0;
@@ -54,10 +71,25 @@  static int simatic_ipc_leds_gpio_remove(struct platform_device *pdev)
 
 static int simatic_ipc_leds_gpio_probe(struct platform_device *pdev)
 {
+	const struct simatic_ipc_platform *plat = pdev->dev.platform_data;
 	struct gpio_desc *gpiod;
 	int err;
 
-	gpiod_add_lookup_table(&simatic_ipc_led_gpio_table);
+	switch (plat->devmode) {
+	case SIMATIC_IPC_DEVICE_127E:
+		simatic_ipc_led_gpio_table = &simatic_ipc_led_gpio_table_127e;
+		break;
+	case SIMATIC_IPC_DEVICE_227G:
+		if (!IS_ENABLED(CONFIG_GPIO_F7188X))
+			return -ENODEV;
+		request_module("gpio-f7188x");
+		simatic_ipc_led_gpio_table = &simatic_ipc_led_gpio_table_227g;
+		break;
+	default:
+		return -ENODEV;
+	}
+
+	gpiod_add_lookup_table(simatic_ipc_led_gpio_table);
 	simatic_leds_pdev = platform_device_register_resndata(NULL,
 		"leds-gpio", PLATFORM_DEVID_NONE, NULL, 0,
 		&simatic_ipc_gpio_leds_pdata,
diff --git a/drivers/platform/x86/simatic-ipc.c b/drivers/platform/x86/simatic-ipc.c
index ca3647b751d5..1825ef21a86d 100644
--- a/drivers/platform/x86/simatic-ipc.c
+++ b/drivers/platform/x86/simatic-ipc.c
@@ -41,6 +41,7 @@  static struct {
 	{SIMATIC_IPC_IPC127E, SIMATIC_IPC_DEVICE_127E, SIMATIC_IPC_DEVICE_NONE},
 	{SIMATIC_IPC_IPC227D, SIMATIC_IPC_DEVICE_227D, SIMATIC_IPC_DEVICE_NONE},
 	{SIMATIC_IPC_IPC227E, SIMATIC_IPC_DEVICE_427E, SIMATIC_IPC_DEVICE_227E},
+	{SIMATIC_IPC_IPC227G, SIMATIC_IPC_DEVICE_227G, SIMATIC_IPC_DEVICE_NONE},
 	{SIMATIC_IPC_IPC277E, SIMATIC_IPC_DEVICE_NONE, SIMATIC_IPC_DEVICE_227E},
 	{SIMATIC_IPC_IPC427D, SIMATIC_IPC_DEVICE_427E, SIMATIC_IPC_DEVICE_NONE},
 	{SIMATIC_IPC_IPC427E, SIMATIC_IPC_DEVICE_427E, SIMATIC_IPC_DEVICE_427E},
@@ -65,7 +66,8 @@  static int register_platform_devices(u32 station_id)
 	}
 
 	if (ledmode != SIMATIC_IPC_DEVICE_NONE) {
-		if (ledmode == SIMATIC_IPC_DEVICE_127E)
+		if (ledmode == SIMATIC_IPC_DEVICE_127E ||
+		    ledmode == SIMATIC_IPC_DEVICE_227G)
 			pdevname = KBUILD_MODNAME "_leds_gpio";
 		platform_data.devmode = ledmode;
 		ipc_led_platform_device =
diff --git a/include/linux/platform_data/x86/simatic-ipc-base.h b/include/linux/platform_data/x86/simatic-ipc-base.h
index 39fefd48cf4d..57d6a10dfc9e 100644
--- a/include/linux/platform_data/x86/simatic-ipc-base.h
+++ b/include/linux/platform_data/x86/simatic-ipc-base.h
@@ -19,6 +19,7 @@ 
 #define SIMATIC_IPC_DEVICE_427E 2
 #define SIMATIC_IPC_DEVICE_127E 3
 #define SIMATIC_IPC_DEVICE_227E 4
+#define SIMATIC_IPC_DEVICE_227G 5
 
 struct simatic_ipc_platform {
 	u8	devmode;
diff --git a/include/linux/platform_data/x86/simatic-ipc.h b/include/linux/platform_data/x86/simatic-ipc.h
index f3b76b39776b..7a2e79f3be0b 100644
--- a/include/linux/platform_data/x86/simatic-ipc.h
+++ b/include/linux/platform_data/x86/simatic-ipc.h
@@ -31,6 +31,7 @@  enum simatic_ipc_station_ids {
 	SIMATIC_IPC_IPC427E = 0x00000A01,
 	SIMATIC_IPC_IPC477E = 0x00000A02,
 	SIMATIC_IPC_IPC127E = 0x00000D01,
+	SIMATIC_IPC_IPC227G = 0x00000F01,
 };
 
 static inline u32 simatic_ipc_get_station_id(u8 *data, int max_len)