[PATCH v2 03/12] platform/apple-gmux: Fix MMIO interface

[Atharva Tiwari]

This patch brings a lot of fixes to MMIO interface such as:
1. Using 1ms waits instead of 100us.
2. Checking if Timed out before reading and writing
3. Adding missing wait before gmux_mmio_write32

Tested-by: Sebastian Zygadlo <szgit@xxxxxxxxxx>
Tested-by: Yossef Osman <yossef.osman@xxxxxxxxx>
Co-developed-by: Andre Eikmeyer <dev@deq.rocks>
Signed-off-by: Andre Eikmeyer <dev@deq.rocks>
Signed-off-by: Atharva Tiwari <atharvatiwarilinuxdev@xxxxxxxxx>
---
 drivers/platform/x86/apple-gmux.c | 60 +++++++++++++++++--------------
 1 file changed, 34 insertions(+), 26 deletions(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 34e94f2b2..9625551e5 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -235,8 +235,8 @@ static int gmux_mmio_wait(struct apple_gmux_data *gmux_data)
 	u8 gwr = ioread8(gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
 
 	while (i && gwr) {
+		fsleep(1000);
 		gwr = ioread8(gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-		udelay(100);
 		i--;
 	}
 
@@ -245,15 +245,16 @@ static int gmux_mmio_wait(struct apple_gmux_data *gmux_data)
 
 static u8 gmux_mmio_read8(struct apple_gmux_data *gmux_data, int port)
 {
-	u8 val;
+	u8 val = 0;
 
 	mutex_lock(&gmux_data->index_lock);
-	gmux_mmio_wait(gmux_data);
-	iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-	iowrite8(GMUX_MMIO_READ | sizeof(val),
-		gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-	gmux_mmio_wait(gmux_data);
-	val = ioread8(gmux_data->iomem_base);
+	if (gmux_mmio_wait(gmux_data)) {
+		iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
+		iowrite8(GMUX_MMIO_READ | sizeof(val),
+			gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+		if (gmux_mmio_wait(gmux_data))
+			val = ioread8(gmux_data->iomem_base);
+	}
 	mutex_unlock(&gmux_data->index_lock);
 
 	return val;
@@ -263,28 +264,33 @@ static void gmux_mmio_write8(struct apple_gmux_data *gmux_data, int port,
 			      u8 val)
 {
 	mutex_lock(&gmux_data->index_lock);
-	gmux_mmio_wait(gmux_data);
-	iowrite8(val, gmux_data->iomem_base);
 
-	iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-	iowrite8(GMUX_MMIO_WRITE | sizeof(val),
-		gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+	if (gmux_mmio_wait(gmux_data)) {
+		iowrite8(val, gmux_data->iomem_base);
 
-	gmux_mmio_wait(gmux_data);
+		iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
+		iowrite8(GMUX_MMIO_WRITE | sizeof(val),
+			gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+
+		/* We already wrote the value there is no point to check if timeout */
+		gmux_mmio_wait(gmux_data);
+	}
 	mutex_unlock(&gmux_data->index_lock);
 }
 
 static u32 gmux_mmio_read32(struct apple_gmux_data *gmux_data, int port)
 {
-	u32 val;
+	u32 val = 0;
 
 	mutex_lock(&gmux_data->index_lock);
-	gmux_mmio_wait(gmux_data);
-	iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-	iowrite8(GMUX_MMIO_READ | sizeof(val),
-		gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-	gmux_mmio_wait(gmux_data);
-	val = ioread32be(gmux_data->iomem_base);
+
+	if (gmux_mmio_wait(gmux_data)) {
+		iowrite8((port & 0xff), gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
+		iowrite8(GMUX_MMIO_READ | sizeof(val),
+			gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+		if (gmux_mmio_wait(gmux_data))
+			val = ioread32be(gmux_data->iomem_base);
+	}
 	mutex_unlock(&gmux_data->index_lock);
 
 	return val;
@@ -294,11 +300,13 @@ static void gmux_mmio_write32(struct apple_gmux_data *gmux_data, int port,
 			       u32 val)
 {
 	mutex_lock(&gmux_data->index_lock);
-	iowrite32be(val, gmux_data->iomem_base);
-	iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
-	iowrite8(GMUX_MMIO_WRITE | sizeof(val),
-		gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
-	gmux_mmio_wait(gmux_data);
+	if (gmux_mmio_wait(gmux_data)) {
+		iowrite32be(val, gmux_data->iomem_base);
+		iowrite8(port & 0xff, gmux_data->iomem_base + GMUX_MMIO_PORT_SELECT);
+		iowrite8(GMUX_MMIO_WRITE | sizeof(val),
+			gmux_data->iomem_base + GMUX_MMIO_COMMAND_SEND);
+		gmux_mmio_wait(gmux_data);
+	}
 	mutex_unlock(&gmux_data->index_lock);
 }
 
-- 
2.55.0