[PATCH v7] hwmon: (it87) Reapply probe path chip registers settings after resume

[Maciej S. Szmigiero]

After a suspend / resume cycle we possibly need to reapply chip registers
settings that we had set or fixed in a probe path, since they might have
been reset to default values or set incorrectly by a BIOS again.

Tested on a Gigabyte M720-US3 board, which requires routing internal VCCH5V
to in7 (and had it wrong again on resume from S3).

Signed-off-by: Maciej S. Szmigiero <mail@xxxxxxxxxxxxxxxxxxxxx>
---
Changes from v1: Move code of common probe / resume steps to new functions
so we don't need to make large parts of probe function conditional on a
newly added 'resume' parameter.

Changes from v2: Code move of common probe / resume steps to new functions
and actual resume functionality split into two, separate patches.

Changed message level about VCCH5V being routed to in7 again on resume to
debug.

Added a "need_in7_reroute" flag and made VCCH5V to in7 rerouting on resume
explicitly conditional on it.

Didn't finally add check for enable_pwm_interface being set before calling
it87_check_pwm() in the resume function since this variable is it87_probe()
function local and so adding this check would require adding it to device
instance structure.

Changes from v3, v4: Fix patch formatting.

Changes from v5: Use 'bool' for on / off variables, don't change it87_find()
function arguments to minimize the changes.

Changes from v6: Add __maybe_unused to it87_resume_sio(), move a message
about failure to enter Super I/O on resume to this function, make it clear
what had actually failed and downgrade it to a warning.

 drivers/hwmon/it87.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 76 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 818f123ac475..a36d5947c1f6 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -497,12 +497,14 @@ static const struct it87_devices it87_devices[] = {
 #define has_vin3_5v(data)	((data)->features & FEAT_VIN3_5V)
 
 struct it87_sio_data {
+	int sioaddr;
 	enum chips type;
 	/* Values read from Super-I/O config space */
 	u8 revision;
 	u8 vid_value;
 	u8 beep_pin;
 	u8 internal;	/* Internal sensors can be labeled */
+	bool need_in7_reroute;
 	/* Features skipped based on config or DMI */
 	u16 skip_in;
 	u8 skip_vid;
@@ -517,6 +519,7 @@ struct it87_sio_data {
  */
 struct it87_data {
 	const struct attribute_group *groups[7];
+	int sioaddr;
 	enum chips type;
 	u32 features;
 	u8 peci_mask;
@@ -532,6 +535,7 @@ struct it87_data {
 	u16 in_internal;	/* Bitfield, internal sensors (for labels) */
 	u16 has_in;		/* Bitfield, voltage sensors enabled */
 	u8 in[NUM_VIN][3];		/* [nr][0]=in, [1]=min, [2]=max */
+	bool need_in7_reroute;
 	u8 has_fan;		/* Bitfield, fans enabled */
 	u16 fan[NUM_FAN][2];	/* Register values, [nr][0]=fan, [1]=min */
 	u8 has_temp;		/* Bitfield, temp sensors enabled */
@@ -2487,6 +2491,7 @@ static int __init it87_find(int sioaddr, unsigned short *address,
 	}
 
 	err = 0;
+	sio_data->sioaddr = sioaddr;
 	sio_data->revision = superio_inb(sioaddr, DEVREV) & 0x0f;
 	pr_info("Found IT%04x%s chip at 0x%x, revision %d\n", chip_type,
 		it87_devices[sio_data->type].suffix,
@@ -2575,6 +2580,7 @@ static int __init it87_find(int sioaddr, unsigned short *address,
 				reg2c |= BIT(1);
 				superio_outb(sioaddr, IT87_SIO_PINX2_REG,
 					     reg2c);
+				sio_data->need_in7_reroute = true;
 				pr_notice("Routing internal VCCH5V to in7.\n");
 			}
 			pr_notice("in7 routed to internal voltage divider, with external pin disabled.\n");
@@ -2777,6 +2783,7 @@ static int __init it87_find(int sioaddr, unsigned short *address,
 		if ((sio_data->type == it8720 || uart6) && !(reg & BIT(1))) {
 			reg |= BIT(1);
 			superio_outb(sioaddr, IT87_SIO_PINX2_REG, reg);
+			sio_data->need_in7_reroute = true;
 			pr_notice("Routing internal VCCH5V to in7\n");
 		}
 		if (reg & BIT(0))
@@ -3024,8 +3031,6 @@ static int it87_check_pwm(struct device *dev)
 				 "PWM configuration is too broken to be fixed\n");
 		}
 
-		dev_info(dev,
-			 "Detected broken BIOS defaults, disabling PWM interface\n");
 		return 0;
 	} else if (fix_pwm_polarity) {
 		dev_info(dev,
@@ -3058,6 +3063,7 @@ static int it87_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	data->addr = res->start;
+	data->sioaddr = sio_data->sioaddr;
 	data->type = sio_data->type;
 	data->features = it87_devices[sio_data->type].features;
 	data->peci_mask = it87_devices[sio_data->type].peci_mask;
@@ -3096,6 +3102,9 @@ static int it87_probe(struct platform_device *pdev)
 
 	/* Check PWM configuration */
 	enable_pwm_interface = it87_check_pwm(dev);
+	if (!enable_pwm_interface)
+		dev_info(dev,
+			 "Detected broken BIOS defaults, disabling PWM interface\n");
 
 	/* Starting with IT8721F, we handle scaling of internal voltages */
 	if (has_12mv_adc(data)) {
@@ -3123,6 +3132,7 @@ static int it87_probe(struct platform_device *pdev)
 	}
 
 	data->in_internal = sio_data->internal;
+	data->need_in7_reroute = sio_data->need_in7_reroute;
 	data->has_in = 0x3ff & ~sio_data->skip_in;
 
 	if (has_six_temp(data)) {
@@ -3178,9 +3188,73 @@ static int it87_probe(struct platform_device *pdev)
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }
 
+static int __maybe_unused it87_resume_sio(struct platform_device *pdev)
+{
+	struct it87_data *data = dev_get_drvdata(&pdev->dev);
+	int err;
+	int reg2c;
+
+	if (!data->need_in7_reroute)
+		return 0;
+
+	err = superio_enter(data->sioaddr);
+	if (err) {
+		dev_warn(&pdev->dev,
+			 "Unable to enter Super I/O to reroute in7 (%d)",
+			 err);
+		return err;
+	}
+
+	superio_select(data->sioaddr, GPIO);
+
+	reg2c = superio_inb(data->sioaddr, IT87_SIO_PINX2_REG);
+	if (!(reg2c & BIT(1))) {
+		dev_dbg(&pdev->dev,
+			"Routing internal VCCH5V to in7 again");
+
+		reg2c |= BIT(1);
+		superio_outb(data->sioaddr, IT87_SIO_PINX2_REG,
+			     reg2c);
+	}
+
+	superio_exit(data->sioaddr);
+
+	return 0;
+}
+
+static int __maybe_unused it87_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct it87_data *data = dev_get_drvdata(dev);
+
+	it87_resume_sio(pdev);
+
+	mutex_lock(&data->update_lock);
+
+	it87_check_pwm(dev);
+	it87_check_limit_regs(data);
+	it87_check_voltage_monitors_reset(data);
+	it87_check_tachometers_reset(pdev);
+	it87_check_tachometers_16bit_mode(pdev);
+
+	it87_start_monitoring(data);
+
+	/* force update */
+	data->valid = 0;
+
+	mutex_unlock(&data->update_lock);
+
+	it87_update_device(dev);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(it87_dev_pm_ops, NULL, it87_resume);
+
 static struct platform_driver it87_driver = {
 	.driver = {
 		.name	= DRVNAME,
+		.pm     = &it87_dev_pm_ops,
 	},
 	.probe	= it87_probe,
 };