hwmon: (it87) Add DMI table for future extensions

Add in DMI matching table to match various board quirks and settings.
This will be useful for future extentions, but will start with the
existing definition of the Shuttle SN68PT.

Signed-off-by: Frank Crawford <frank@crawford.emu.id.au>
Link: https://lore.kernel.org/r/20221105232531.1619387-1-frank@crawford.emu.id.au
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 53 insertions, 19 deletions

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 73ed21ab325b..9997f76b1f4a 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -567,6 +567,14 @@ struct it87_data {
 	s8 auto_temp[NUM_AUTO_PWM][5];	/* [nr][0] is point1_temp_hyst */
 };
 
+/* Board specific settings from DMI matching */
+struct it87_dmi_data {
+	u8 skip_pwm;		/* pwm channels to skip for this board  */
+};
+
+/* Global for results from DMI matching, if needed */
+static struct it87_dmi_data *dmi_data;
+
 static int adc_lsb(const struct it87_data *data, int nr)
 {
 	int lsb;
@@ -2393,7 +2401,6 @@ static int __init it87_find(int sioaddr, unsigned short *address,
 {
 	int err;
 	u16 chip_type;
-	const char *board_vendor, *board_name;
 	const struct it87_devices *config;
 
 	err = superio_enter(sioaddr);
@@ -2812,24 +2819,9 @@ static int __init it87_find(int sioaddr, unsigned short *address,
 	if (sio_data->beep_pin)
 		pr_info("Beeping is supported\n");
 
-	/* Disable specific features based on DMI strings */
-	board_vendor = dmi_get_system_info(DMI_BOARD_VENDOR);
-	board_name = dmi_get_system_info(DMI_BOARD_NAME);
-	if (board_vendor && board_name) {
-		if (strcmp(board_vendor, "nVIDIA") == 0 &&
-		    strcmp(board_name, "FN68PT") == 0) {
-			/*
-			 * On the Shuttle SN68PT, FAN_CTL2 is apparently not
-			 * connected to a fan, but to something else. One user
-			 * has reported instant system power-off when changing
-			 * the PWM2 duty cycle, so we disable it.
-			 * I use the board name string as the trigger in case
-			 * the same board is ever used in other systems.
-			 */
-			pr_info("Disabling pwm2 due to hardware constraints\n");
-			sio_data->skip_pwm = BIT(1);
-		}
-	}
+	/* Set values based on DMI matches */
+	if (dmi_data)
+		sio_data->skip_pwm |= dmi_data->skip_pwm;
 
 exit:
 	superio_exit(sioaddr);
@@ -3307,6 +3299,46 @@ exit_device_put:
 	return err;
 }
 
+/* callback function for DMI */
+static int it87_dmi_cb(const struct dmi_system_id *dmi_entry)
+{
+	dmi_data = dmi_entry->driver_data;
+
+	if (dmi_data && dmi_data->skip_pwm)
+		pr_info("Disabling pwm2 due to hardware constraints\n");
+
+	return 1;
+}
+
+/*
+ * On the Shuttle SN68PT, FAN_CTL2 is apparently not
+ * connected to a fan, but to something else. One user
+ * has reported instant system power-off when changing
+ * the PWM2 duty cycle, so we disable it.
+ * I use the board name string as the trigger in case
+ * the same board is ever used in other systems.
+ */
+static struct it87_dmi_data nvidia_fn68pt = {
+	.skip_pwm = BIT(1),
+};
+
+#define IT87_DMI_MATCH_VND(vendor, name, cb, data) \
+	{ \
+		.callback = cb, \
+		.matches = { \
+			DMI_EXACT_MATCH(DMI_BOARD_VENDOR, vendor), \
+			DMI_EXACT_MATCH(DMI_BOARD_NAME, name), \
+		}, \
+		.driver_data = data, \
+	}
+
+static const struct dmi_system_id it87_dmi_table[] __initconst = {
+	IT87_DMI_MATCH_VND("nVIDIA", "FN68PT", it87_dmi_cb, &nvidia_fn68pt),
+	{ }
+
+};
+MODULE_DEVICE_TABLE(dmi, it87_dmi_table);
+
 static int __init sm_it87_init(void)
 {
 	int sioaddr[2] = { REG_2E, REG_4E };
@@ -3319,6 +3351,8 @@ static int __init sm_it87_init(void)
 	if (err)
 		return err;
 
+	dmi_check_system(it87_dmi_table);
+
 	for (i = 0; i < ARRAY_SIZE(sioaddr); i++) {
 		memset(&sio_data, 0, sizeof(struct it87_sio_data));
 		isa_address[i] = 0;