[PATCH 03/13] 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

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 | 59 ++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 24 deletions(-)

diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c
index 4e8786a5e..076ed7ba6 100644
--- a/drivers/platform/x86/apple-gmux.c
+++ b/drivers/platform/x86/apple-gmux.c
@@ -237,8 +237,8 @@ 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--;
 	}
 
@@ -250,12 +250,14 @@ static u8 gmux_mmio_read8(struct apple_gmux_data *gmux_data, int port)
 	u8 val;
 
 	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))
+			return 0;
+		val = ioread8(gmux_data->iomem_base);
+	}
 	mutex_unlock(&gmux_data->index_lock);
 
 	return val;
@@ -265,14 +267,17 @@ 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);
 }
 
@@ -281,12 +286,16 @@ static u32 gmux_mmio_read32(struct apple_gmux_data *gmux_data, int port)
 	u32 val;
 
 	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))
+			return 0;
+
+		val = ioread32be(gmux_data->iomem_base);
+	}
 	mutex_unlock(&gmux_data->index_lock);
 
 	return val;
@@ -296,11 +305,13 @@ 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