drm/i915: index gmbus tables using the pin pair number

Index the gmbus tables directly using the pin instead of having a
confusing "port = i + 1" mapping. This finishes off removing the "gmbus
port" as a notion, and leaves us with just the "gmbus pin".

As pin 0 is invalid by definition and the gmbus tables will have a gap
at that index, add pin validity check to all the loops. This will be
benefitial for supporting platforms that have different numbers of pins,
or gaps.

v2: s/GMBUS_PIN_MAX/GMBUS_NUM_PINS/ (Ville, Daniel)
Reviewed-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: NJani Nikula <jani.nikula@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1574,8 +1574,7 @@ struct drm_i915_private {
 
 	struct i915_virtual_gpu vgpu;
 
-	struct intel_gmbus gmbus[GMBUS_NUM_PORTS];
-
+	struct intel_gmbus gmbus[GMBUS_NUM_PINS];
 
 	/** gmbus_mutex protects against concurrent usage of the single hw gmbus
 	 * controller on different i2c buses. */

drivers/gpu/drm/i915/i915_reg.h

@@ -1797,7 +1797,7 @@ enum skl_disp_power_wells {
 #define   GMBUS_PIN_DPB		5 /* SDVO, HDMIB */
 #define   GMBUS_PIN_DPD		6 /* HDMID */
 #define   GMBUS_PIN_RESERVED	7 /* 7 reserved */
-#define   GMBUS_NUM_PORTS	(GMBUS_PIN_DPD - GMBUS_PIN_SSC + 1)
+#define   GMBUS_NUM_PINS	7 /* including 0 */
 #define GMBUS1			0x5104 /* command/status */
 #define   GMBUS_SW_CLR_INT	(1<<31)
 #define   GMBUS_SW_RDY		(1<<30)

drivers/gpu/drm/i915/intel_i2c.c

@@ -34,18 +34,19 @@
 #include <drm/i915_drm.h>
 #include "i915_drv.h"
 
-struct gmbus_port {
+struct gmbus_pin {
 	const char *name;
 	int reg;
 };
 
-static const struct gmbus_port gmbus_ports[] = {
-	{ "ssc", GPIOB },
-	{ "vga", GPIOA },
-	{ "panel", GPIOC },
-	{ "dpc", GPIOD },
-	{ "dpb", GPIOE },
-	{ "dpd", GPIOF },
+/* Map gmbus pin pairs to names and registers. */
+static const struct gmbus_pin gmbus_pins[] = {
+	[GMBUS_PIN_SSC] = { "ssc", GPIOB },
+	[GMBUS_PIN_VGADDC] = { "vga", GPIOA },
+	[GMBUS_PIN_PANEL] = { "panel", GPIOC },
+	[GMBUS_PIN_DPC] = { "dpc", GPIOD },
+	[GMBUS_PIN_DPB] = { "dpb", GPIOE },
+	[GMBUS_PIN_DPD] = { "dpd", GPIOF },
 };
 
 /* Intel GPIO access functions */
@@ -182,15 +183,14 @@ intel_gpio_post_xfer(struct i2c_adapter *adapter)
 }
 
 static void
-intel_gpio_setup(struct intel_gmbus *bus, u32 pin)
+intel_gpio_setup(struct intel_gmbus *bus, unsigned int pin)
 {
 	struct drm_i915_private *dev_priv = bus->dev_priv;
 	struct i2c_algo_bit_data *algo;
 
 	algo = &bus->bit_algo;
 
-	/* -1 to map pin pair to gmbus index */
-	bus->gpio_reg = dev_priv->gpio_mmio_base + gmbus_ports[pin - 1].reg;
+	bus->gpio_reg = dev_priv->gpio_mmio_base + gmbus_pins[pin].reg;
 
 	bus->adapter.algo_data = algo;
 	algo->setsda = set_data;
@@ -517,7 +517,9 @@ static const struct i2c_algorithm gmbus_algorithm = {
 int intel_setup_gmbus(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	int ret, i;
+	struct intel_gmbus *bus;
+	unsigned int pin;
+	int ret;
 
 	if (HAS_PCH_NOP(dev))
 		return 0;
@@ -531,16 +533,18 @@ int intel_setup_gmbus(struct drm_device *dev)
 	mutex_init(&dev_priv->gmbus_mutex);
 	init_waitqueue_head(&dev_priv->gmbus_wait_queue);
 
-	for (i = 0; i < GMBUS_NUM_PORTS; i++) {
-		struct intel_gmbus *bus = &dev_priv->gmbus[i];
-		u32 port = i + 1; /* +1 to map gmbus index to pin pair */
+	for (pin = 0; pin < ARRAY_SIZE(dev_priv->gmbus); pin++) {
+		if (!intel_gmbus_is_valid_pin(pin))
+			continue;
+
+		bus = &dev_priv->gmbus[pin];
 
 		bus->adapter.owner = THIS_MODULE;
 		bus->adapter.class = I2C_CLASS_DDC;
 		snprintf(bus->adapter.name,
 			 sizeof(bus->adapter.name),
 			 "i915 gmbus %s",
-			 gmbus_ports[i].name);
+			 gmbus_pins[pin].name);
 
 		bus->adapter.dev.parent = &dev->pdev->dev;
 		bus->dev_priv = dev_priv;
@@ -548,13 +552,13 @@ int intel_setup_gmbus(struct drm_device *dev)
 		bus->adapter.algo = &gmbus_algorithm;
 
 		/* By default use a conservative clock rate */
-		bus->reg0 = port | GMBUS_RATE_100KHZ;
+		bus->reg0 = pin | GMBUS_RATE_100KHZ;
 
 		/* gmbus seems to be broken on i830 */
 		if (IS_I830(dev))
 			bus->force_bit = 1;
 
-		intel_gpio_setup(bus, port);
+		intel_gpio_setup(bus, pin);
 
 		ret = i2c_add_adapter(&bus->adapter);
 		if (ret)
@@ -566,8 +570,11 @@ int intel_setup_gmbus(struct drm_device *dev)
 	return 0;
 
 err:
-	while (--i) {
-		struct intel_gmbus *bus = &dev_priv->gmbus[i];
+	while (--pin) {
+		if (!intel_gmbus_is_valid_pin(pin))
+			continue;
+
+		bus = &dev_priv->gmbus[pin];
 		i2c_del_adapter(&bus->adapter);
 	}
 	return ret;
@@ -576,10 +583,10 @@ int intel_setup_gmbus(struct drm_device *dev)
 struct i2c_adapter *intel_gmbus_get_adapter(struct drm_i915_private *dev_priv,
 					    unsigned int pin)
 {
-	WARN_ON(!intel_gmbus_is_valid_pin(pin));
-	/* -1 to map pin pair to gmbus index */
-	return (intel_gmbus_is_valid_pin(pin)) ?
-		&dev_priv->gmbus[pin - 1].adapter : NULL;
+	if (WARN_ON(!intel_gmbus_is_valid_pin(pin)))
+		return NULL;
+
+	return &dev_priv->gmbus[pin].adapter;
 }
 
 void intel_gmbus_set_speed(struct i2c_adapter *adapter, int speed)
@@ -602,10 +609,14 @@ void intel_gmbus_force_bit(struct i2c_adapter *adapter, bool force_bit)
 void intel_teardown_gmbus(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
-	int i;
+	struct intel_gmbus *bus;
+	unsigned int pin;
+
+	for (pin = 0; pin < ARRAY_SIZE(dev_priv->gmbus); pin++) {
+		if (!intel_gmbus_is_valid_pin(pin))
+			continue;
 
-	for (i = 0; i < GMBUS_NUM_PORTS; i++) {
-		struct intel_gmbus *bus = &dev_priv->gmbus[i];
+		bus = &dev_priv->gmbus[pin];
 		i2c_del_adapter(&bus->adapter);
 	}
 }