net: ipa: use a separate pointer for adjusted GSI memory

This patch actually fixes a bug, though it doesn't affect the two
platforms supported currently.  The fix implements GSI memory
pointers a bit differently.

For IPA version 4.5 and above, the address space for almost all GSI
registers is adjusted downward by a fixed amount.  This is currently
handled by adjusting the I/O virtual address pointer after it has
been mapped.  The bug is that the pointer is not "de-adjusted" as it
should be when it's unmapped.

This patch fixes that error, but it does so by maintaining one "raw"
pointer for the mapped memory range.  This is assigned when the
memory is mapped and used to unmap the memory.  This pointer is also
used to access the two registers that do *not* sit in the "adjusted"
memory space.

Rather than adjusting *that* pointer, we maintain a separate pointer
that's an adjusted copy of the "raw" pointer, and that is used for
most GSI register accesses.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 12 insertions, 16 deletions

diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
index 440213646188..9c977f80109a 100644
--- a/drivers/net/ipa/gsi.c
+++ b/drivers/net/ipa/gsi.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 /* Copyright (c) 2015-2018, The Linux Foundation. All rights reserved.
- * Copyright (C) 2018-2020 Linaro Ltd.
+ * Copyright (C) 2018-2021 Linaro Ltd.
  */
 
 #include <linux/types.h>
@@ -195,8 +195,6 @@ static void gsi_irq_type_disable(struct gsi *gsi, enum gsi_irq_type_id type_id)
 /* Turn off all GSI interrupts initially */
 static void gsi_irq_setup(struct gsi *gsi)
 {
-	u32 adjust;
-
 	/* Disable all interrupt types */
 	gsi_irq_type_update(gsi, 0);
 
@@ -206,10 +204,9 @@ static void gsi_irq_setup(struct gsi *gsi)
 	iowrite32(0, gsi->virt + GSI_CNTXT_GLOB_IRQ_EN_OFFSET);
 	iowrite32(0, gsi->virt + GSI_CNTXT_SRC_IEOB_IRQ_MSK_OFFSET);
 
-	/* Reverse the offset adjustment for inter-EE register offsets */
-	adjust = gsi->version < IPA_VERSION_4_5 ? 0 : GSI_EE_REG_ADJUST;
-	iowrite32(0, gsi->virt + adjust + GSI_INTER_EE_SRC_CH_IRQ_OFFSET);
-	iowrite32(0, gsi->virt + adjust + GSI_INTER_EE_SRC_EV_CH_IRQ_OFFSET);
+	/* The inter-EE registers are in the non-adjusted address range */
+	iowrite32(0, gsi->virt_raw + GSI_INTER_EE_SRC_CH_IRQ_OFFSET);
+	iowrite32(0, gsi->virt_raw + GSI_INTER_EE_SRC_EV_CH_IRQ_OFFSET);
 
 	iowrite32(0, gsi->virt + GSI_CNTXT_GSI_IRQ_EN_OFFSET);
 }
@@ -2181,9 +2178,8 @@ int gsi_init(struct gsi *gsi, struct platform_device *pdev,
 	gsi->dev = dev;
 	gsi->version = version;
 
-	/* The GSI layer performs NAPI on all endpoints.  NAPI requires a
-	 * network device structure, but the GSI layer does not have one,
-	 * so we must create a dummy network device for this purpose.
+	/* GSI uses NAPI on all channels.  Create a dummy network device
+	 * for the channel NAPI contexts to be associated with.
 	 */
 	init_dummy_netdev(&gsi->dummy_dev);
 
@@ -2208,13 +2204,13 @@ int gsi_init(struct gsi *gsi, struct platform_device *pdev,
 		return -EINVAL;
 	}
 
-	gsi->virt = ioremap(res->start, size);
-	if (!gsi->virt) {
+	gsi->virt_raw = ioremap(res->start, size);
+	if (!gsi->virt_raw) {
 		dev_err(dev, "unable to remap \"gsi\" memory\n");
 		return -ENOMEM;
 	}
-	/* Adjust register range pointer downward for newer IPA versions */
-	gsi->virt -= adjust;
+	/* Most registers are accessed using an adjusted register range */
+	gsi->virt = gsi->virt_raw - adjust;
 
 	init_completion(&gsi->completion);
 
@@ -2233,7 +2229,7 @@ int gsi_init(struct gsi *gsi, struct platform_device *pdev,
 err_irq_exit:
 	gsi_irq_exit(gsi);
 err_iounmap:
-	iounmap(gsi->virt);
+	iounmap(gsi->virt_raw);
 
 	return ret;
 }
@@ -2244,7 +2240,7 @@ void gsi_exit(struct gsi *gsi)
 	mutex_destroy(&gsi->mutex);
 	gsi_channel_exit(gsi);
 	gsi_irq_exit(gsi);
-	iounmap(gsi->virt);
+	iounmap(gsi->virt_raw);
 }
 
 /* The maximum number of outstanding TREs on a channel.  This limits