apple_gmux: Add support for newer hardware

New gmux devices have a different method for accessing the registers.
Update the driver to cope. Incorporates feedback from Bernhard Froemel.
Signed-off-by: Matthew Garrett <mjg@redhat.com>
Cc: Bernhard Froemel <froemel@vmars.tuwien.ac.at>
Cc: Seth Forshee <seth.forshee@canonical.com>

drivers/platform/x86/apple-gmux.c

@@ -18,12 +18,15 @@
 #include <linux/pnp.h>
 #include <linux/apple_bl.h>
 #include <linux/slab.h>
+#include <linux/delay.h>
 #include <acpi/video.h>
 #include <asm/io.h>
 
 struct apple_gmux_data {
 	unsigned long iostart;
 	unsigned long iolen;
+	bool indexed;
+	struct mutex index_lock;
 
 	struct backlight_device *bdev;
 };
@@ -45,6 +48,9 @@ struct apple_gmux_data {
 #define GMUX_PORT_DISCRETE_POWER	0x50
 #define GMUX_PORT_MAX_BRIGHTNESS	0x70
 #define GMUX_PORT_BRIGHTNESS		0x74
+#define GMUX_PORT_VALUE			0xc2
+#define GMUX_PORT_READ			0xd0
+#define GMUX_PORT_WRITE			0xd4
 
 #define GMUX_MIN_IO_LEN			(GMUX_PORT_BRIGHTNESS + 4)
 
@@ -59,23 +65,23 @@ struct apple_gmux_data {
 #define GMUX_BRIGHTNESS_MASK		0x00ffffff
 #define GMUX_MAX_BRIGHTNESS		GMUX_BRIGHTNESS_MASK
 
-static inline u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
+static u8 gmux_pio_read8(struct apple_gmux_data *gmux_data, int port)
 {
 	return inb(gmux_data->iostart + port);
 }
 
-static inline void gmux_write8(struct apple_gmux_data *gmux_data, int port,
+static void gmux_pio_write8(struct apple_gmux_data *gmux_data, int port,
 			       u8 val)
 {
 	outb(val, gmux_data->iostart + port);
 }
 
-static inline u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
+static u32 gmux_pio_read32(struct apple_gmux_data *gmux_data, int port)
 {
 	return inl(gmux_data->iostart + port);
 }
 
-static inline u32 gmux_write32(struct apple_gmux_data *gmux_data, int port,
+static void gmux_pio_write32(struct apple_gmux_data *gmux_data, int port,
 			     u32 val)
 {
 	int i;
@@ -87,6 +93,144 @@ static inline u32 gmux_write32(struct apple_gmux_data *gmux_data, int port,
 	}
 }
 
+static int gmux_index_wait_ready(struct apple_gmux_data *gmux_data)
+{
+	int i = 200;
+	u8 gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+
+	while (i && (gwr & 0x01)) {
+		inb(gmux_data->iostart + GMUX_PORT_READ);
+		gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+		udelay(100);
+		i--;
+	}
+
+	return !!i;
+}
+
+static int gmux_index_wait_complete(struct apple_gmux_data *gmux_data)
+{
+	int i = 200;
+	u8 gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+
+	while (i && !(gwr & 0x01)) {
+		gwr = inb(gmux_data->iostart + GMUX_PORT_WRITE);
+		udelay(100);
+		i--;
+	}
+
+	if (gwr & 0x01)
+		inb(gmux_data->iostart + GMUX_PORT_READ);
+
+	return !!i;
+}
+
+static u8 gmux_index_read8(struct apple_gmux_data *gmux_data, int port)
+{
+	u8 val;
+
+	mutex_lock(&gmux_data->index_lock);
+	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
+	gmux_index_wait_ready(gmux_data);
+	val = inb(gmux_data->iostart + GMUX_PORT_VALUE);
+	mutex_unlock(&gmux_data->index_lock);
+
+	return val;
+}
+
+static void gmux_index_write8(struct apple_gmux_data *gmux_data, int port,
+			      u8 val)
+{
+	mutex_lock(&gmux_data->index_lock);
+	outb(val, gmux_data->iostart + GMUX_PORT_VALUE);
+	gmux_index_wait_ready(gmux_data);
+	outb(port & 0xff, gmux_data->iostart + GMUX_PORT_WRITE);
+	gmux_index_wait_complete(gmux_data);
+	mutex_unlock(&gmux_data->index_lock);
+}
+
+static u32 gmux_index_read32(struct apple_gmux_data *gmux_data, int port)
+{
+	u32 val;
+
+	mutex_lock(&gmux_data->index_lock);
+	outb((port & 0xff), gmux_data->iostart + GMUX_PORT_READ);
+	gmux_index_wait_ready(gmux_data);
+	val = inl(gmux_data->iostart + GMUX_PORT_VALUE);
+	mutex_unlock(&gmux_data->index_lock);
+
+	return val;
+}
+
+static void gmux_index_write32(struct apple_gmux_data *gmux_data, int port,
+			       u32 val)
+{
+	int i;
+	u8 tmpval;
+
+	mutex_lock(&gmux_data->index_lock);
+
+	for (i = 0; i < 4; i++) {
+		tmpval = (val >> (i * 8)) & 0xff;
+		outb(tmpval, gmux_data->iostart + GMUX_PORT_VALUE + i);
+	}
+
+	gmux_index_wait_ready(gmux_data);
+	outb(port & 0xff, gmux_data->iostart + GMUX_PORT_WRITE);
+	gmux_index_wait_complete(gmux_data);
+	mutex_unlock(&gmux_data->index_lock);
+}
+
+static u8 gmux_read8(struct apple_gmux_data *gmux_data, int port)
+{
+	if (gmux_data->indexed)
+		return gmux_index_read8(gmux_data, port);
+	else
+		return gmux_pio_read8(gmux_data, port);
+}
+
+static void gmux_write8(struct apple_gmux_data *gmux_data, int port, u8 val)
+{
+	if (gmux_data->indexed)
+		gmux_index_write8(gmux_data, port, val);
+	else
+		gmux_pio_write8(gmux_data, port, val);
+}
+
+static u32 gmux_read32(struct apple_gmux_data *gmux_data, int port)
+{
+	if (gmux_data->indexed)
+		return gmux_index_read32(gmux_data, port);
+	else
+		return gmux_pio_read32(gmux_data, port);
+}
+
+static void gmux_write32(struct apple_gmux_data *gmux_data, int port,
+			     u32 val)
+{
+	if (gmux_data->indexed)
+		gmux_index_write32(gmux_data, port, val);
+	else
+		gmux_pio_write32(gmux_data, port, val);
+}
+
+static bool gmux_is_indexed(struct apple_gmux_data *gmux_data)
+{
+	u16 val;
+
+	outb(0xaa, gmux_data->iostart + 0xcc);
+	outb(0x55, gmux_data->iostart + 0xcd);
+	outb(0x00, gmux_data->iostart + 0xce);
+
+	val = inb(gmux_data->iostart + 0xcc) |
+		(inb(gmux_data->iostart + 0xcd) << 8);
+
+	if (val == 0x55aa)
+		return true;
+
+	return false;
+}
+
 static int gmux_get_brightness(struct backlight_device *bd)
 {
 	struct apple_gmux_data *gmux_data = bl_get_data(bd);
@@ -150,21 +294,28 @@ static int __devinit gmux_probe(struct pnp_dev *pnp,
 	}
 
 	/*
-	 * On some machines the gmux is in ACPI even thought the machine
-	 * doesn't really have a gmux. Check for invalid version information
-	 * to detect this.
+	 * Invalid version information may indicate either that the gmux
+	 * device isn't present or that it's a new one that uses indexed
+	 * io
 	 */
+
 	ver_major = gmux_read8(gmux_data, GMUX_PORT_VERSION_MAJOR);
 	ver_minor = gmux_read8(gmux_data, GMUX_PORT_VERSION_MINOR);
 	ver_release = gmux_read8(gmux_data, GMUX_PORT_VERSION_RELEASE);
 	if (ver_major == 0xff && ver_minor == 0xff && ver_release == 0xff) {
+		if (gmux_is_indexed(gmux_data)) {
+			mutex_init(&gmux_data->index_lock);
+			gmux_data->indexed = true;
+		} else {
 			pr_info("gmux device not present\n");
 			ret = -ENODEV;
 			goto err_release;
 		}
-
+		pr_info("Found indexed gmux\n");
+	} else {
 		pr_info("Found gmux version %d.%d.%d\n", ver_major, ver_minor,
 			ver_release);
+	}
 
 	memset(&props, 0, sizeof(props));
 	props.type = BACKLIGHT_PLATFORM;