staging: vc04_services: vchiq_arm: Drop g_cache_line_size

The cache-line-size is cached in struct vchiq_platform_info.
There is no need to cache this again via g_cache_line_size
and use it. Instead use the value from vchiq_platform_info directly.

While at it, move the comment about L2 cache line size in the kerneldoc
block of struct vchiq_platform_info.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Stefan Wahren <wahrenst@gmx.net>
Link: https://lore.kernel.org/r/20240412075743.60712-4-umang.jain@ideasonboard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c

@@ -131,17 +131,6 @@ struct vchiq_pagelist_info {
 };
 
 static void __iomem *g_regs;
-/* This value is the size of the L2 cache lines as understood by the
- * VPU firmware, which determines the required alignment of the
- * offsets/sizes in pagelists.
- *
- * Modern VPU firmware looks for a DT "cache-line-size" property in
- * the VCHIQ node and will overwrite it with the actual L2 cache size,
- * which the kernel must then respect.  That property was rejected
- * upstream, so we have to use the VPU firmware's compatibility value
- * of 32.
- */
-static unsigned int g_cache_line_size = 32;
 static unsigned int g_fragments_size;
 static char *g_fragments_base;
 static char *g_free_fragments;
@@ -212,6 +201,7 @@ static struct vchiq_pagelist_info *
 create_pagelist(struct vchiq_instance *instance, char *buf, char __user *ubuf,
 		size_t count, unsigned short type)
 {
+	struct vchiq_drv_mgmt *drv_mgmt;
 	struct pagelist *pagelist;
 	struct vchiq_pagelist_info *pagelistinfo;
 	struct page **pages;
@@ -226,6 +216,8 @@ create_pagelist(struct vchiq_instance *instance, char *buf, char __user *ubuf,
 	if (count >= INT_MAX - PAGE_SIZE)
 		return NULL;
 
+	drv_mgmt = dev_get_drvdata(instance->state->dev->parent);
+
 	if (buf)
 		offset = (uintptr_t)buf & (PAGE_SIZE - 1);
 	else
@@ -368,9 +360,9 @@ create_pagelist(struct vchiq_instance *instance, char *buf, char __user *ubuf,
 
 	/* Partial cache lines (fragments) require special measures */
 	if ((type == PAGELIST_READ) &&
-	    ((pagelist->offset & (g_cache_line_size - 1)) ||
+	    ((pagelist->offset & (drv_mgmt->info->cache_line_size - 1)) ||
 	    ((pagelist->offset + pagelist->length) &
-	    (g_cache_line_size - 1)))) {
+	    (drv_mgmt->info->cache_line_size - 1)))) {
 		char *fragments;
 
 		if (down_interruptible(&g_free_fragments_sema)) {
@@ -396,12 +388,15 @@ static void
 free_pagelist(struct vchiq_instance *instance, struct vchiq_pagelist_info *pagelistinfo,
 	      int actual)
 {
+	struct vchiq_drv_mgmt *drv_mgmt;
 	struct pagelist *pagelist = pagelistinfo->pagelist;
 	struct page **pages = pagelistinfo->pages;
 	unsigned int num_pages = pagelistinfo->num_pages;
 
 	dev_dbg(instance->state->dev, "arm: %pK, %d\n", pagelistinfo->pagelist, actual);
 
+	drv_mgmt = dev_get_drvdata(instance->state->dev->parent);
+
 	/*
 	 * NOTE: dma_unmap_sg must be called before the
 	 * cpu can touch any of the data/pages.
@@ -417,10 +412,10 @@ free_pagelist(struct vchiq_instance *instance, struct vchiq_pagelist_info *pagel
 			g_fragments_size;
 		int head_bytes, tail_bytes;
 
-		head_bytes = (g_cache_line_size - pagelist->offset) &
-			(g_cache_line_size - 1);
+		head_bytes = (drv_mgmt->info->cache_line_size - pagelist->offset) &
+			(drv_mgmt->info->cache_line_size - 1);
 		tail_bytes = (pagelist->offset + actual) &
-			(g_cache_line_size - 1);
+			(drv_mgmt->info->cache_line_size - 1);
 
 		if ((actual >= 0) && (head_bytes != 0)) {
 			if (head_bytes > actual)
@@ -435,8 +430,8 @@ free_pagelist(struct vchiq_instance *instance, struct vchiq_pagelist_info *pagel
 		    (tail_bytes != 0))
 			memcpy_to_page(pages[num_pages - 1],
 				(pagelist->offset + actual) &
-				(PAGE_SIZE - 1) & ~(g_cache_line_size - 1),
-				fragments + g_cache_line_size,
+				(PAGE_SIZE - 1) & ~(drv_mgmt->info->cache_line_size - 1),
+				fragments + drv_mgmt->info->cache_line_size,
 				tail_bytes);
 
 		down(&g_free_fragments_mutex);
@@ -479,8 +474,7 @@ static int vchiq_platform_init(struct platform_device *pdev, struct vchiq_state
 	if (err < 0)
 		return err;
 
-	g_cache_line_size = drv_mgmt->info->cache_line_size;
-	g_fragments_size = 2 * g_cache_line_size;
+	g_fragments_size = 2 * drv_mgmt->info->cache_line_size;
 
 	/* Allocate space for the channels in coherent memory */
 	slot_mem_size = PAGE_ALIGN(TOTAL_SLOTS * VCHIQ_SLOT_SIZE);

drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.h

@@ -20,11 +20,22 @@
 #define MAX_ELEMENTS 8
 #define MSG_QUEUE_SIZE 128
 
+struct rpi_firmware;
+
 enum USE_TYPE_E {
 	USE_TYPE_SERVICE,
 	USE_TYPE_VCHIQ
 };
 
+struct vchiq_platform_info {
+	unsigned int cache_line_size;
+};
+
+struct vchiq_drv_mgmt {
+	struct rpi_firmware *fw;
+	const struct vchiq_platform_info *info;
+};
+
 struct user_service {
 	struct vchiq_service *service;
 	void __user *userdata;