Date:	Sat, 16 Jan 2016 16:19:22 +0100
From:	Pali Rohár <pali.rohar@...il.com>
To:	Michał Kępień <kernel@...pniu.pl>
Cc:	Darren Hart <dvhart@...radead.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Richard Purdie <rpurdie@...ys.net>,
	Jacek Anaszewski <j.anaszewski@...sung.com>,
	Alex Hung <alex.hung@...onical.com>,
	platform-driver-x86@...r.kernel.org, linux-leds@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/14] dell-laptop: extract SMBIOS-related code to a
 separate module

On Tuesday 12 January 2016 15:02:47 Michał Kępień wrote:
> Extract SMBIOS-related code from dell-laptop to a new kernel module,
> dell-smbios.  The static specifier was removed from exported symbols,
> otherwise code is just moved around.
> 
> Signed-off-by: Michał Kępień <kernel@...pniu.pl>
> ---
>  drivers/platform/x86/Kconfig       |   12 ++-
>  drivers/platform/x86/Makefile      |    1 +
>  drivers/platform/x86/dell-laptop.c |  163 +-----------------------------
>  drivers/platform/x86/dell-smbios.c |  193 ++++++++++++++++++++++++++++++++++++
>  drivers/platform/x86/dell-smbios.h |   51 ++++++++++
>  5 files changed, 257 insertions(+), 163 deletions(-)
>  create mode 100644 drivers/platform/x86/dell-smbios.c
>  create mode 100644 drivers/platform/x86/dell-smbios.h
> 
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index f37821f..177a794 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -91,10 +91,20 @@ config ASUS_LAPTOP
>  
>  	  If you have an ACPI-compatible ASUS laptop, say Y or M here.
>  
> +config DELL_SMBIOS
> +	tristate "Dell SMBIOS Support"
> +	depends on DCDBAS
> +	default n
> +	---help---
> +	This module provides common functions for kernel modules using
> +	Dell SMBIOS.
> +
> +	If you have a Dell laptop, say Y or M here.
> +
>  config DELL_LAPTOP
>  	tristate "Dell Laptop Extras"
>  	depends on X86
> -	depends on DCDBAS
> +	depends on DELL_SMBIOS
>  	depends on BACKLIGHT_CLASS_DEVICE
>  	depends on ACPI_VIDEO || ACPI_VIDEO = n
>  	depends on RFKILL || RFKILL = n
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 8b8df29..1128595 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_EEEPC_WMI)		+= eeepc-wmi.o
>  obj-$(CONFIG_MSI_LAPTOP)	+= msi-laptop.o
>  obj-$(CONFIG_ACPI_CMPC)		+= classmate-laptop.o
>  obj-$(CONFIG_COMPAL_LAPTOP)	+= compal-laptop.o
> +obj-$(CONFIG_DELL_SMBIOS)	+= dell-smbios.o
>  obj-$(CONFIG_DELL_LAPTOP)	+= dell-laptop.o
>  obj-$(CONFIG_DELL_WMI)		+= dell-wmi.o
>  obj-$(CONFIG_DELL_WMI_AIO)	+= dell-wmi-aio.o
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index aaeeae8..d45d356 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -28,12 +28,11 @@
>  #include <linux/acpi.h>
>  #include <linux/mm.h>
>  #include <linux/i8042.h>
> -#include <linux/slab.h>
>  #include <linux/debugfs.h>
>  #include <linux/seq_file.h>
>  #include <acpi/video.h>
> -#include "../../firmware/dcdbas.h"
>  #include "dell-rbtn.h"
> +#include "dell-smbios.h"
>  
>  #define BRIGHTNESS_TOKEN 0x7d
>  #define KBD_LED_OFF_TOKEN 0x01E1
> @@ -44,33 +43,6 @@
>  #define KBD_LED_AUTO_75_TOKEN 0x02EC
>  #define KBD_LED_AUTO_100_TOKEN 0x02F6
>  
> -/* This structure will be modified by the firmware when we enter
> - * system management mode, hence the volatiles */
> -
> -struct calling_interface_buffer {
> -	u16 class;
> -	u16 select;
> -	volatile u32 input[4];
> -	volatile u32 output[4];
> -} __packed;
> -
> -struct calling_interface_token {
> -	u16 tokenID;
> -	u16 location;
> -	union {
> -		u16 value;
> -		u16 stringlength;
> -	};
> -};
> -
> -struct calling_interface_structure {
> -	struct dmi_header header;
> -	u16 cmdIOAddress;
> -	u8 cmdIOCode;
> -	u32 supportedCmds;
> -	struct calling_interface_token tokens[];
> -} __packed;
> -
>  struct quirk_entry {
>  	u8 touchpad_led;
>  
> @@ -103,11 +75,6 @@ static struct quirk_entry quirk_dell_xps13_9333 = {
>  	.kbd_timeouts = { 0, 5, 15, 60, 5 * 60, 15 * 60, -1 },
>  };
>  
> -static int da_command_address;
> -static int da_command_code;
> -static int da_num_tokens;
> -static struct calling_interface_token *da_tokens;
> -
>  static struct platform_driver platform_driver = {
>  	.driver = {
>  		.name = "dell-laptop",
> @@ -306,112 +273,6 @@ static const struct dmi_system_id dell_quirks[] __initconst = {
>  	{ }
>  };
>  
> -static struct calling_interface_buffer *buffer;
> -static DEFINE_MUTEX(buffer_mutex);
> -
> -static void clear_buffer(void)
> -{
> -	memset(buffer, 0, sizeof(struct calling_interface_buffer));
> -}
> -
> -static void get_buffer(void)
> -{
> -	mutex_lock(&buffer_mutex);
> -	clear_buffer();
> -}
> -
> -static void release_buffer(void)
> -{
> -	mutex_unlock(&buffer_mutex);
> -}
> -
> -static void __init parse_da_table(const struct dmi_header *dm)
> -{
> -	/* Final token is a terminator, so we don't want to copy it */
> -	int tokens = (dm->length-11)/sizeof(struct calling_interface_token)-1;
> -	struct calling_interface_token *new_da_tokens;
> -	struct calling_interface_structure *table =
> -		container_of(dm, struct calling_interface_structure, header);
> -
> -	/* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
> -	   6 bytes of entry */
> -
> -	if (dm->length < 17)
> -		return;
> -
> -	da_command_address = table->cmdIOAddress;
> -	da_command_code = table->cmdIOCode;
> -
> -	new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
> -				 sizeof(struct calling_interface_token),
> -				 GFP_KERNEL);
> -
> -	if (!new_da_tokens)
> -		return;
> -	da_tokens = new_da_tokens;
> -
> -	memcpy(da_tokens+da_num_tokens, table->tokens,
> -	       sizeof(struct calling_interface_token) * tokens);
> -
> -	da_num_tokens += tokens;
> -}
> -
> -static void __init find_tokens(const struct dmi_header *dm, void *dummy)
> -{
> -	switch (dm->type) {
> -	case 0xd4: /* Indexed IO */
> -	case 0xd5: /* Protected Area Type 1 */
> -	case 0xd6: /* Protected Area Type 2 */
> -		break;
> -	case 0xda: /* Calling interface */
> -		parse_da_table(dm);
> -		break;
> -	}
> -}
> -
> -static int find_token_id(int tokenid)
> -{
> -	int i;
> -
> -	for (i = 0; i < da_num_tokens; i++) {
> -		if (da_tokens[i].tokenID == tokenid)
> -			return i;
> -	}
> -
> -	return -1;
> -}
> -
> -static int find_token_location(int tokenid)
> -{
> -	int id;
> -
> -	id = find_token_id(tokenid);
> -	if (id == -1)
> -		return -1;
> -
> -	return da_tokens[id].location;
> -}
> -
> -static struct calling_interface_buffer *
> -dell_send_request(struct calling_interface_buffer *buffer, int class,
> -		  int select)
> -{
> -	struct smi_cmd command;
> -
> -	command.magic = SMI_CMD_MAGIC;
> -	command.command_address = da_command_address;
> -	command.command_code = da_command_code;
> -	command.ebx = virt_to_phys(buffer);
> -	command.ecx = 0x42534931;
> -
> -	buffer->class = class;
> -	buffer->select = select;
> -
> -	dcdbas_smi_request(&command);
> -
> -	return buffer;
> -}
> -
>  static inline int dell_smi_error(int value)
>  {
>  	switch (value) {
> @@ -2122,13 +1983,6 @@ static int __init dell_init(void)
>  	/* find if this machine support other functions */
>  	dmi_check_system(dell_quirks);
>  
> -	dmi_walk(find_tokens, NULL);
> -
> -	if (!da_tokens)  {
> -		pr_info("Unable to find dmi tokens\n");
> -		return -ENODEV;
> -	}
> -
>  	ret = platform_driver_register(&platform_driver);
>  	if (ret)
>  		goto fail_platform_driver;
> @@ -2141,16 +1995,6 @@ static int __init dell_init(void)
>  	if (ret)
>  		goto fail_platform_device2;
>  
> -	/*
> -	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
> -	 * is passed to SMI handler.
> -	 */
> -	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
> -	if (!buffer) {
> -		ret = -ENOMEM;
> -		goto fail_buffer;
> -	}
> -
>  	ret = dell_setup_rfkill();
>  
>  	if (ret) {
> @@ -2208,15 +2052,12 @@ static int __init dell_init(void)
>  fail_backlight:
>  	dell_cleanup_rfkill();
>  fail_rfkill:
> -	free_page((unsigned long)buffer);
> -fail_buffer:
>  	platform_device_del(platform_device);
>  fail_platform_device2:
>  	platform_device_put(platform_device);
>  fail_platform_device1:
>  	platform_driver_unregister(&platform_driver);
>  fail_platform_driver:
> -	kfree(da_tokens);
>  	return ret;
>  }
>  
> @@ -2232,8 +2073,6 @@ static void __exit dell_exit(void)
>  		platform_device_unregister(platform_device);
>  		platform_driver_unregister(&platform_driver);
>  	}
> -	kfree(da_tokens);
> -	free_page((unsigned long)buffer);
>  }
>  
>  /* dell-rbtn.c driver export functions which will not work correctly (and could
> diff --git a/drivers/platform/x86/dell-smbios.c b/drivers/platform/x86/dell-smbios.c
> new file mode 100644
> index 0000000..260a32a
> --- /dev/null
> +++ b/drivers/platform/x86/dell-smbios.c
> @@ -0,0 +1,193 @@
> +/*
> + *  Common functions for kernel modules using Dell SMBIOS
> + *
> + *  Copyright (c) Red Hat <mjg@...hat.com>
> + *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@...il.com>
> + *  Copyright (c) 2014 Pali Rohár <pali.rohar@...il.com>
> + *
> + *  Based on documentation in the libsmbios package:
> + *  Copyright (C) 2005-2014 Dell Inc.
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License version 2 as
> + *  published by the Free Software Foundation.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/dmi.h>
> +#include <linux/gfp.h>
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +#include "../../firmware/dcdbas.h"
> +#include "dell-smbios.h"
> +
> +struct calling_interface_structure {
> +	struct dmi_header header;
> +	u16 cmdIOAddress;
> +	u8 cmdIOCode;
> +	u32 supportedCmds;
> +	struct calling_interface_token tokens[];
> +} __packed;
> +
> +static DEFINE_MUTEX(buffer_mutex);
> +struct calling_interface_buffer *buffer;
> +EXPORT_SYMBOL_GPL(buffer);
> +
> +static int da_command_address;
> +static int da_command_code;
> +static int da_num_tokens;
> +struct calling_interface_token *da_tokens;
> +EXPORT_SYMBOL_GPL(da_tokens);
> +
> +void clear_buffer(void)
> +{
> +	memset(buffer, 0, sizeof(struct calling_interface_buffer));
> +}
> +EXPORT_SYMBOL_GPL(clear_buffer);
> +
> +void get_buffer(void)
> +{
> +	mutex_lock(&buffer_mutex);
> +	clear_buffer();
> +}
> +EXPORT_SYMBOL_GPL(get_buffer);
> +
> +void release_buffer(void)
> +{
> +	mutex_unlock(&buffer_mutex);
> +}
> +EXPORT_SYMBOL_GPL(release_buffer);
> +
> +int find_token_id(int tokenid)
> +{
> +	int i;
> +
> +	for (i = 0; i < da_num_tokens; i++) {
> +		if (da_tokens[i].tokenID == tokenid)
> +			return i;
> +	}
> +
> +	return -1;
> +}
> +EXPORT_SYMBOL_GPL(find_token_id);
> +
> +int find_token_location(int tokenid)
> +{
> +	int id;
> +
> +	id = find_token_id(tokenid);
> +	if (id == -1)
> +		return -1;
> +
> +	return da_tokens[id].location;
> +}
> +EXPORT_SYMBOL_GPL(find_token_location);
> +
> +struct calling_interface_buffer *
> +dell_send_request(struct calling_interface_buffer *buffer, int class,
> +		  int select)
> +{
> +	struct smi_cmd command;
> +
> +	command.magic = SMI_CMD_MAGIC;
> +	command.command_address = da_command_address;
> +	command.command_code = da_command_code;
> +	command.ebx = virt_to_phys(buffer);
> +	command.ecx = 0x42534931;
> +
> +	buffer->class = class;
> +	buffer->select = select;
> +
> +	dcdbas_smi_request(&command);
> +
> +	return buffer;
> +}
> +EXPORT_SYMBOL_GPL(dell_send_request);
> +
> +static void __init parse_da_table(const struct dmi_header *dm)
> +{
> +	/* Final token is a terminator, so we don't want to copy it */
> +	int tokens = (dm->length-11)/sizeof(struct calling_interface_token)-1;
> +	struct calling_interface_token *new_da_tokens;
> +	struct calling_interface_structure *table =
> +		container_of(dm, struct calling_interface_structure, header);
> +
> +	/* 4 bytes of table header, plus 7 bytes of Dell header, plus at least
> +	   6 bytes of entry */
> +
> +	if (dm->length < 17)
> +		return;
> +
> +	da_command_address = table->cmdIOAddress;
> +	da_command_code = table->cmdIOCode;
> +
> +	new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
> +				 sizeof(struct calling_interface_token),
> +				 GFP_KERNEL);
> +
> +	if (!new_da_tokens)
> +		return;
> +	da_tokens = new_da_tokens;
> +
> +	memcpy(da_tokens+da_num_tokens, table->tokens,
> +	       sizeof(struct calling_interface_token) * tokens);
> +
> +	da_num_tokens += tokens;
> +}
> +
> +static void __init find_tokens(const struct dmi_header *dm, void *dummy)
> +{
> +	switch (dm->type) {
> +	case 0xd4: /* Indexed IO */
> +	case 0xd5: /* Protected Area Type 1 */
> +	case 0xd6: /* Protected Area Type 2 */
> +		break;
> +	case 0xda: /* Calling interface */
> +		parse_da_table(dm);
> +		break;
> +	}
> +}
> +
> +static int __init dell_smbios_init(void)
> +{
> +	int ret;
> +
> +	dmi_walk(find_tokens, NULL);
> +
> +	if (!da_tokens)  {
> +		pr_info("Unable to find dmi tokens\n");
> +		return -ENODEV;
> +	}
> +
> +	/*
> +	 * Allocate buffer below 4GB for SMI data--only 32-bit physical addr
> +	 * is passed to SMI handler.
> +	 */
> +	buffer = (void *)__get_free_page(GFP_KERNEL | GFP_DMA32);
> +	if (!buffer) {
> +		ret = -ENOMEM;
> +		goto fail_buffer;
> +	}
> +
> +	return 0;
> +
> +fail_buffer:
> +	kfree(da_tokens);
> +	return ret;
> +}
> +
> +static void __exit dell_smbios_exit(void)
> +{
> +	kfree(da_tokens);
> +	free_page((unsigned long)buffer);
> +}
> +
> +subsys_initcall(dell_smbios_init);
> +module_exit(dell_smbios_exit);
> +
> +MODULE_AUTHOR("Matthew Garrett <mjg@...hat.com>");
> +MODULE_AUTHOR("Gabriele Mazzotta <gabriele.mzt@...il.com>");
> +MODULE_AUTHOR("Pali Rohár <pali.rohar@...il.com>");
> +MODULE_DESCRIPTION("Common functions for kernel modules using Dell SMBIOS");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/platform/x86/dell-smbios.h b/drivers/platform/x86/dell-smbios.h
> new file mode 100644
> index 0000000..00e03b2
> --- /dev/null
> +++ b/drivers/platform/x86/dell-smbios.h
> @@ -0,0 +1,51 @@
> +/*
> + *  Common functions for kernel modules using Dell SMBIOS
> + *
> + *  Copyright (c) Red Hat <mjg@...hat.com>
> + *  Copyright (c) 2014 Gabriele Mazzotta <gabriele.mzt@...il.com>
> + *  Copyright (c) 2014 Pali Rohár <pali.rohar@...il.com>
> + *
> + *  Based on documentation in the libsmbios package:
> + *  Copyright (C) 2005-2014 Dell Inc.
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License version 2 as
> + *  published by the Free Software Foundation.
> + */
> +
> +#ifndef _DELL_SMBIOS_H_
> +#define _DELL_SMBIOS_H_
> +
> +/* This structure will be modified by the firmware when we enter
> + * system management mode, hence the volatiles */
> +
> +struct calling_interface_buffer {
> +	u16 class;
> +	u16 select;
> +	volatile u32 input[4];
> +	volatile u32 output[4];
> +} __packed;
> +
> +struct calling_interface_token {
> +	u16 tokenID;
> +	u16 location;
> +	union {
> +		u16 value;
> +		u16 stringlength;
> +	};
> +};

After patch 12/14 you do not need to define this struct in header file.

> +extern struct calling_interface_buffer *buffer;
> +extern struct calling_interface_token *da_tokens;

Better hide this variable in dell-smbios.c code ...

> +void clear_buffer(void);
> +void get_buffer(void);
> +void release_buffer(void);

... and let those functions to get parameter to buffer.

E.g. get_buffer will return buffer and other two functions will take
buffer parameter.

> +int find_token_id(int tokenid);
> +int find_token_location(int tokenid);
> +
> +struct calling_interface_buffer *
> +dell_send_request(struct calling_interface_buffer *buffer, int class,
> +		  int select);
> +#endif

-- 
Pali Rohár
pali.rohar@...il.com

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