[PATCH 3/6] drm/simpledrm: Add support for system memory framebuffers
Thierry Reding
thierry.reding at gmail.com
Mon Sep 5 16:32:57 UTC 2022
From: Thierry Reding <treding at nvidia.com>
Simple framebuffers can be set up in system memory, which cannot be
requested and/or I/O remapped using the I/O resource helpers. Add a
separate code path that obtains system memory framebuffers from the
reserved memory region referenced in the memory-region property.
Signed-off-by: Thierry Reding <treding at nvidia.com>
---
drivers/gpu/drm/tiny/simpledrm.c | 166 +++++++++++++++++++++++++------
1 file changed, 135 insertions(+), 31 deletions(-)
diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index a81f91814595..16377b39f012 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -2,6 +2,7 @@
#include <linux/clk.h>
#include <linux/of_clk.h>
+#include <linux/of_reserved_mem.h>
#include <linux/minmax.h>
#include <linux/platform_data/simplefb.h>
#include <linux/platform_device.h>
@@ -218,6 +219,8 @@ struct simpledrm_device {
/* memory management */
void __iomem *screen_base;
+ phys_addr_t sysmem_start;
+ size_t sysmem_size;
/* modesetting */
uint32_t formats[8];
@@ -451,6 +454,100 @@ static int simpledrm_device_init_regulators(struct simpledrm_device *sdev)
}
#endif
+/*
+ * Memory management
+ */
+
+static int simpledrm_device_init_mm_sysmem(struct simpledrm_device *sdev, phys_addr_t start,
+ size_t size)
+{
+ struct drm_device *dev = &sdev->dev;
+ phys_addr_t end = start + size - 1;
+
+ drm_info(dev, "using system memory framebuffer at [%pa-%pa]\n", &start, &end);
+
+ sdev->screen_base = devm_memremap(dev->dev, start, size, MEMREMAP_WC);
+ if (!sdev->screen_base)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static int simpledrm_device_init_mm_io(struct simpledrm_device *sdev, phys_addr_t start,
+ size_t size)
+{
+ struct drm_device *dev = &sdev->dev;
+ phys_addr_t end = start + size - 1;
+ struct resource *mem;
+
+ drm_info(dev, "using I/O memory framebuffer at [%pa-%pa]\n", &start, &end);
+
+ mem = devm_request_mem_region(dev->dev, start, size, sdev->dev.driver->name);
+ if (!mem) {
+ /*
+ * We cannot make this fatal. Sometimes this comes from magic
+ * spaces our resource handlers simply don't know about. Use
+ * the I/O-memory resource as-is and try to map that instead.
+ */
+ drm_warn(dev, "could not acquire memory region [%pa-%pa]\n", &start, &end);
+ } else {
+ size = resource_size(mem);
+ start = mem->start;
+ }
+
+ sdev->screen_base = devm_ioremap_wc(dev->dev, start, size);
+ if (!sdev->screen_base)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void simpledrm_device_exit_mm(void *data)
+{
+ struct simpledrm_device *sdev = data;
+ struct drm_device *dev = &sdev->dev;
+
+ of_reserved_mem_device_release(dev->dev);
+}
+
+static int simpledrm_device_init_mm(struct simpledrm_device *sdev)
+{
+ int (*init)(struct simpledrm_device *sdev, phys_addr_t start, size_t size);
+ struct drm_device *dev = &sdev->dev;
+ struct platform_device *pdev = to_platform_device(dev->dev);
+ phys_addr_t start, end;
+ size_t size;
+ int ret;
+
+ ret = of_reserved_mem_device_init_by_idx(dev->dev, dev->dev->of_node, 0);
+ if (ret) {
+ struct resource *res;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -EINVAL;
+
+ init = simpledrm_device_init_mm_io;
+ size = resource_size(res);
+ start = res->start;
+ } else {
+ devm_add_action_or_reset(dev->dev, simpledrm_device_exit_mm, sdev);
+ init = simpledrm_device_init_mm_sysmem;
+ start = sdev->sysmem_start;
+ size = sdev->sysmem_size;
+ }
+
+ end = start + size - 1;
+
+ ret = devm_aperture_acquire_from_firmware(dev, start, size);
+ if (ret) {
+ drm_err(dev, "could not acquire memory range [%pa-%pa]: %d\n", &start, &end, ret);
+ return ret;
+ }
+
+ return init(sdev, start, size);
+}
+
/*
* Modesetting
*/
@@ -511,13 +608,18 @@ static void simpledrm_primary_plane_helper_atomic_update(struct drm_plane *plane
struct drm_framebuffer *fb = plane_state->fb;
struct drm_device *dev = plane->dev;
struct simpledrm_device *sdev = simpledrm_device_of_dev(dev);
- struct iosys_map dst = IOSYS_MAP_INIT_VADDR(sdev->screen_base);
struct drm_rect src_clip, dst_clip;
+ struct iosys_map dst;
int idx;
if (!fb)
return;
+ if (sdev->sysmem_size == 0)
+ iosys_map_set_vaddr_iomem(&dst, sdev->screen_base);
+ else
+ iosys_map_set_vaddr(&dst, sdev->screen_base);
+
if (!drm_atomic_helper_damage_merged(old_plane_state, plane_state, &src_clip))
return;
@@ -721,8 +823,6 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
struct drm_device *dev;
int width, height, stride;
const struct drm_format_info *format;
- struct resource *res, *mem;
- void __iomem *screen_base;
struct drm_plane *primary_plane;
struct drm_crtc *crtc;
struct drm_encoder *encoder;
@@ -790,35 +890,9 @@ static struct simpledrm_device *simpledrm_device_create(struct drm_driver *drv,
drm_dbg(dev, "framebuffer format=%p4cc, size=%dx%d, stride=%d byte\n",
&format->format, width, height, stride);
- /*
- * Memory management
- */
-
- res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- if (!res)
- return ERR_PTR(-EINVAL);
-
- ret = devm_aperture_acquire_from_firmware(dev, res->start, resource_size(res));
- if (ret) {
- drm_err(dev, "could not acquire memory range %pr: error %d\n", res, ret);
+ ret = simpledrm_device_init_mm(sdev);
+ if (ret)
return ERR_PTR(ret);
- }
-
- mem = devm_request_mem_region(&pdev->dev, res->start, resource_size(res), drv->name);
- if (!mem) {
- /*
- * We cannot make this fatal. Sometimes this comes from magic
- * spaces our resource handlers simply don't know about. Use
- * the I/O-memory resource as-is and try to map that instead.
- */
- drm_warn(dev, "could not acquire memory region %pr\n", res);
- mem = res;
- }
-
- screen_base = devm_ioremap_wc(&pdev->dev, mem->start, resource_size(mem));
- if (!screen_base)
- return ERR_PTR(-ENOMEM);
- sdev->screen_base = screen_base;
/*
* Modesetting
@@ -959,5 +1033,35 @@ static struct platform_driver simpledrm_platform_driver = {
module_platform_driver(simpledrm_platform_driver);
+static int simple_framebuffer_device_init(struct reserved_mem *rmem, struct device *dev)
+{
+ struct simpledrm_device *sdev = dev_get_drvdata(dev);
+
+ sdev->sysmem_start = rmem->base;
+ sdev->sysmem_size = rmem->size;
+
+ return 0;
+}
+
+static void simple_framebuffer_device_release(struct reserved_mem *rmem, struct device *dev)
+{
+}
+
+static const struct reserved_mem_ops simple_framebuffer_ops = {
+ .device_init = simple_framebuffer_device_init,
+ .device_release = simple_framebuffer_device_release,
+};
+
+static int simple_framebuffer_init(struct reserved_mem *rmem)
+{
+ pr_info("framebuffer memory at %pa, size %lu bytes\n", &rmem->base,
+ (unsigned long)rmem->size);
+
+ rmem->ops = &simple_framebuffer_ops;
+
+ return 0;
+}
+RESERVEDMEM_OF_DECLARE(simple_framebuffer, "framebuffer", simple_framebuffer_init);
+
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL v2");
--
2.37.2
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