hwmon: Allow to compile dell-smm-hwmon driver without /proc/i8k

This patch splits CONFIG_I8K compile option to SENSORS_DELL_SMM and CONFIG_I8K.
Option SENSORS_DELL_SMM is now used to enable compilation of dell-smm-hwmon
driver and old CONFIG_I8K option to enable /proc/i8k interface in driver.

So this change allows to compile dell-smm-hwmon driver without legacy /proc/i8k
interface which is needed only for old Dell Inspirion models or for userspace
i8kutils package.

For backward compatibility when CONFIG_I8K is enabled then also SENSORS_DELL_SMM
is enabled and so driver dell-smm-hwmon (with /proc/i8k) is compiled.
Signed-off-by: NPali Rohár <pali.rohar@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/x86/Kconfig

@@ -1055,24 +1055,19 @@ config TOSHIBA
 	  Say N otherwise.
 
 config I8K
-	tristate "Dell laptop support"
+	tristate "Dell i8k legacy laptop support"
 	select HWMON
+	select SENSORS_DELL_SMM
 	---help---
-	  This adds a driver to safely access the System Management Mode
-	  of the CPU on the Dell Inspiron 8000. The System Management Mode
-	  is used to read cpu temperature and cooling fan status and to
-	  control the fans on the I8K portables.
+	  This option enables legacy /proc/i8k userspace interface in hwmon
+	  dell-smm-hwmon driver. Character file /proc/i8k reports bios version,
+	  temperature and allows controlling fan speeds of Dell laptops via
+	  System Management Mode. For old Dell laptops (like Dell Inspiron 8000)
+	  it reports also power and hotkey status. For fan speed control is
+	  needed userspace package i8kutils.
 
-	  This driver has been tested only on the Inspiron 8000 but it may
-	  also work with other Dell laptops. You can force loading on other
-	  models by passing the parameter `force=1' to the module. Use at
-	  your own risk.
-
-	  For information on utilities to make use of this driver see the
-	  I8K Linux utilities web site at:
-	  <http://people.debian.org/~dz/i8k/>
-
-	  Say Y if you intend to run this kernel on a Dell Inspiron 8000.
+	  Say Y if you intend to run this kernel on old Dell laptops or want to
+	  use userspace package i8kutils.
 	  Say N otherwise.
 
 config X86_REBOOTFIXUPS

drivers/hwmon/Kconfig

@@ -371,6 +371,17 @@ config SENSORS_DS1621
 	  This driver can also be built as a module.  If so, the module
 	  will be called ds1621.
 
+config SENSORS_DELL_SMM
+	tristate "Dell laptop SMM BIOS hwmon driver"
+	depends on X86
+	help
+	  This hwmon driver adds support for reporting temperature of different
+	  sensors and controls the fans on Dell laptops via System Management
+	  Mode provided by Dell BIOS.
+
+	  When option I8K is also enabled this driver provides legacy /proc/i8k
+	  userspace interface for i8kutils package.
+
 config SENSORS_DA9052_ADC
 	tristate "Dialog DA9052/DA9053 ADC"
 	depends on PMIC_DA9052

drivers/hwmon/Makefile

@@ -49,6 +49,7 @@ obj-$(CONFIG_SENSORS_ATXP1)	+= atxp1.o
 obj-$(CONFIG_SENSORS_CORETEMP)	+= coretemp.o
 obj-$(CONFIG_SENSORS_DA9052_ADC)+= da9052-hwmon.o
 obj-$(CONFIG_SENSORS_DA9055)+= da9055-hwmon.o
+obj-$(CONFIG_SENSORS_DELL_SMM)	+= dell-smm-hwmon.o
 obj-$(CONFIG_SENSORS_DME1737)	+= dme1737.o
 obj-$(CONFIG_SENSORS_DS620)	+= ds620.o
 obj-$(CONFIG_SENSORS_DS1621)	+= ds1621.o
@@ -156,7 +157,6 @@ obj-$(CONFIG_SENSORS_W83L785TS)	+= w83l785ts.o
 obj-$(CONFIG_SENSORS_W83L786NG)	+= w83l786ng.o
 obj-$(CONFIG_SENSORS_WM831X)	+= wm831x-hwmon.o
 obj-$(CONFIG_SENSORS_WM8350)	+= wm8350-hwmon.o
-obj-$(CONFIG_I8K)		+= dell-smm-hwmon.o
 
 obj-$(CONFIG_PMBUS)		+= pmbus/
 

drivers/hwmon/dell-smm-hwmon.c

@@ -81,7 +81,7 @@ static uint i8k_fan_max = I8K_FAN_HIGH;
 
 MODULE_AUTHOR("Massimo Dal Zotto (dz@debian.org)");
 MODULE_AUTHOR("Pali Rohár <pali.rohar@gmail.com>");
-MODULE_DESCRIPTION("Driver for accessing SMM BIOS on Dell laptops");
+MODULE_DESCRIPTION("Dell laptop SMM BIOS hwmon driver");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("i8k");
 
@@ -93,6 +93,7 @@ static bool ignore_dmi;
 module_param(ignore_dmi, bool, 0);
 MODULE_PARM_DESC(ignore_dmi, "Continue probing hardware even if DMI data does not match");
 
+#if IS_ENABLED(CONFIG_I8K)
 static bool restricted;
 module_param(restricted, bool, 0);
 MODULE_PARM_DESC(restricted, "Allow fan control if SYS_ADMIN capability set");
@@ -100,6 +101,7 @@ MODULE_PARM_DESC(restricted, "Allow fan control if SYS_ADMIN capability set");
 static bool power_status;
 module_param(power_status, bool, 0600);
 MODULE_PARM_DESC(power_status, "Report power status in /proc/i8k");
+#endif
 
 static uint fan_mult;
 module_param(fan_mult, uint, 0);
@@ -109,18 +111,6 @@ static uint fan_max;
 module_param(fan_max, uint, 0);
 MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed (default: autodetect)");
 
-static int i8k_open_fs(struct inode *inode, struct file *file);
-static long i8k_ioctl(struct file *, unsigned int, unsigned long);
-
-static const struct file_operations i8k_fops = {
-	.owner		= THIS_MODULE,
-	.open		= i8k_open_fs,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-	.unlocked_ioctl	= i8k_ioctl,
-};
-
 struct smm_regs {
 	unsigned int eax;
 	unsigned int ebx __packed;
@@ -220,45 +210,6 @@ static int i8k_smm(struct smm_regs *regs)
 	return rc;
 }
 
-/*
- * Read the Fn key status.
- */
-static int i8k_get_fn_status(void)
-{
-	struct smm_regs regs = { .eax = I8K_SMM_FN_STATUS, };
-	int rc;
-
-	rc = i8k_smm(&regs);
-	if (rc < 0)
-		return rc;
-
-	switch ((regs.eax >> I8K_FN_SHIFT) & I8K_FN_MASK) {
-	case I8K_FN_UP:
-		return I8K_VOL_UP;
-	case I8K_FN_DOWN:
-		return I8K_VOL_DOWN;
-	case I8K_FN_MUTE:
-		return I8K_VOL_MUTE;
-	default:
-		return 0;
-	}
-}
-
-/*
- * Read the power status.
- */
-static int i8k_get_power_status(void)
-{
-	struct smm_regs regs = { .eax = I8K_SMM_POWER_STATUS, };
-	int rc;
-
-	rc = i8k_smm(&regs);
-	if (rc < 0)
-		return rc;
-
-	return (regs.eax & 0xff) == I8K_POWER_AC ? I8K_AC : I8K_BATTERY;
-}
-
 /*
  * Read the fan status.
  */
@@ -378,6 +329,51 @@ static int i8k_get_dell_signature(int req_fn)
 	return regs.eax == 1145651527 && regs.edx == 1145392204 ? 0 : -1;
 }
 
+#if IS_ENABLED(CONFIG_I8K)
+
+/*
+ * Read the Fn key status.
+ */
+static int i8k_get_fn_status(void)
+{
+	struct smm_regs regs = { .eax = I8K_SMM_FN_STATUS, };
+	int rc;
+
+	rc = i8k_smm(&regs);
+	if (rc < 0)
+		return rc;
+
+	switch ((regs.eax >> I8K_FN_SHIFT) & I8K_FN_MASK) {
+	case I8K_FN_UP:
+		return I8K_VOL_UP;
+	case I8K_FN_DOWN:
+		return I8K_VOL_DOWN;
+	case I8K_FN_MUTE:
+		return I8K_VOL_MUTE;
+	default:
+		return 0;
+	}
+}
+
+/*
+ * Read the power status.
+ */
+static int i8k_get_power_status(void)
+{
+	struct smm_regs regs = { .eax = I8K_SMM_POWER_STATUS, };
+	int rc;
+
+	rc = i8k_smm(&regs);
+	if (rc < 0)
+		return rc;
+
+	return (regs.eax & 0xff) == I8K_POWER_AC ? I8K_AC : I8K_BATTERY;
+}
+
+/*
+ * Procfs interface
+ */
+
 static int
 i8k_ioctl_unlocked(struct file *fp, unsigned int cmd, unsigned long arg)
 {
@@ -528,6 +524,37 @@ static int i8k_open_fs(struct inode *inode, struct file *file)
 	return single_open(file, i8k_proc_show, NULL);
 }
 
+static const struct file_operations i8k_fops = {
+	.owner		= THIS_MODULE,
+	.open		= i8k_open_fs,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+	.unlocked_ioctl	= i8k_ioctl,
+};
+
+static void __init i8k_init_procfs(void)
+{
+	/* Register the proc entry */
+	proc_create("i8k", 0, NULL, &i8k_fops);
+}
+
+static void __exit i8k_exit_procfs(void)
+{
+	remove_proc_entry("i8k", NULL);
+}
+
+#else
+
+static inline void __init i8k_init_procfs(void)
+{
+}
+
+static inline void __exit i8k_exit_procfs(void)
+{
+}
+
+#endif
 
 /*
  * Hwmon interface
@@ -750,8 +777,8 @@ static int __init i8k_init_hwmon(void)
 	if (err >= 0)
 		i8k_hwmon_flags |= I8K_HWMON_HAVE_FAN2;
 
-	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "i8k", NULL,
-							  i8k_groups);
+	i8k_hwmon_dev = hwmon_device_register_with_groups(NULL, "dell-smm",
+							  NULL, i8k_groups);
 	if (IS_ERR(i8k_hwmon_dev)) {
 		err = PTR_ERR(i8k_hwmon_dev);
 		i8k_hwmon_dev = NULL;
@@ -976,33 +1003,24 @@ static int __init i8k_probe(void)
 
 static int __init i8k_init(void)
 {
-	struct proc_dir_entry *proc_i8k;
 	int err;
 
 	/* Are we running on an supported laptop? */
 	if (i8k_probe())
 		return -ENODEV;
 
-	/* Register the proc entry */
-	proc_i8k = proc_create("i8k", 0, NULL, &i8k_fops);
-	if (!proc_i8k)
-		return -ENOENT;
-
 	err = i8k_init_hwmon();
 	if (err)
-		goto exit_remove_proc;
+		return err;
 
+	i8k_init_procfs();
 	return 0;
-
- exit_remove_proc:
-	remove_proc_entry("i8k", NULL);
-	return err;
 }
 
 static void __exit i8k_exit(void)
 {
 	hwmon_device_unregister(i8k_hwmon_dev);
-	remove_proc_entry("i8k", NULL);
+	i8k_exit_procfs();
 }
 
 module_init(i8k_init);