Hi Am 18.05.22 um 23:11 schrieb Mark Cave-Ayland:
On 18/05/2022 19:30, Thomas Zimmermann wrote:Open Firmware provides basic display output via the 'display' node. DT platform code already provides a device that represents the node's framebuffer. Add a DRM driver for the device. The display mode and color format is pre-initialized by the system's firmware. Runtime modesetting via DRM is not possible. The display is useful during early boot stages or as error fallback. Similar functionality is already provided by fbdev's offb driver, which is insufficient for modern userspace. The old driver includes support for BootX device tree, which can be found on old 32-bit PowerPC Macintosh systems. If these are still in use, the functionality can be added to ofdrm or implemented in a new driver. As with simepldrm, the fbdev driver cannot be selected is ofdrm is already enabled. Two noteable points about the driver: * Reading the framebuffer aperture from the device tree is not reliable on all systems. Ofdrm takes the heuristics and a comment from offb to pick the correct range. * No resource management may be tied to the underlying PCI device. Otherwise the handover to the native driver will fail with a resource conflict. PCI management is therefore done as part of the platform device's cleanup. The driver has been tested on qemu's ppc64le emulation. The device hand-over has been tested with bochs.Thanks for working on this! Have you tried it on qemu-system-sparc and qemu-system-sparc64 at all? At least under QEMU I'd expect it to work for these platforms too, unless there is a particular dependency on PCI. A couple of comments inline below:
I haven't tried Sparc, as the old offb driver only supports PPC.I was already wondering why Sparc isn't supported. I wouldn't mind if we can add it.
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> --- MAINTAINERS | 1 + drivers/gpu/drm/tiny/Kconfig | 12 + drivers/gpu/drm/tiny/Makefile | 1 + drivers/gpu/drm/tiny/ofdrm.c | 748 ++++++++++++++++++++++++++++++++++ drivers/video/fbdev/Kconfig | 1 + 5 files changed, 763 insertions(+) create mode 100644 drivers/gpu/drm/tiny/ofdrm.c diff --git a/MAINTAINERS b/MAINTAINERS index 43d833273ae9..090cbe1aa5e3 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6395,6 +6395,7 @@ L: dri-devel@xxxxxxxxxxxxxxxxxxxxx S: Maintained T: git git://anongit.freedesktop.org/drm/drm-misc F: drivers/gpu/drm/drm_aperture.c +F: drivers/gpu/drm/tiny/ofdrm.c F: drivers/gpu/drm/tiny/simpledrm.c F: include/drm/drm_aperture.h diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig index 627d637a1e7e..0bc54af42e7f 100644 --- a/drivers/gpu/drm/tiny/Kconfig +++ b/drivers/gpu/drm/tiny/Kconfig @@ -51,6 +51,18 @@ config DRM_GM12U320 This is a KMS driver for projectors which use the GM12U320 chipsetfor video transfer over USB2/3, such as the Acer C120 mini projector.+config DRM_OFDRM + tristate "Open Firmware display driver" + depends on DRM && MMU && PPC + select DRM_GEM_SHMEM_HELPER + select DRM_KMS_HELPER + help + DRM driver for Open Firmware framebuffers. + + This driver assumes that the display hardware has been initialized+ by the Open Firmware before the kernel boots. Scanout buffer, size,+ and display format must be provided via device tree. + config DRM_PANEL_MIPI_DBI tristate "DRM support for MIPI DBI compatible panels" depends on DRM && SPIdiff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefileindex 1d9d6227e7ab..76dde89a044b 100644 --- a/drivers/gpu/drm/tiny/Makefile +++ b/drivers/gpu/drm/tiny/Makefile @@ -4,6 +4,7 @@ obj-$(CONFIG_DRM_ARCPGU) += arcpgu.o obj-$(CONFIG_DRM_BOCHS) += bochs.o obj-$(CONFIG_DRM_CIRRUS_QEMU) += cirrus.o obj-$(CONFIG_DRM_GM12U320) += gm12u320.o +obj-$(CONFIG_DRM_OFDRM) += ofdrm.o obj-$(CONFIG_DRM_PANEL_MIPI_DBI) += panel-mipi-dbi.o obj-$(CONFIG_DRM_SIMPLEDRM) += simpledrm.o obj-$(CONFIG_TINYDRM_HX8357D) += hx8357d.o diff --git a/drivers/gpu/drm/tiny/ofdrm.c b/drivers/gpu/drm/tiny/ofdrm.c new file mode 100644 index 000000000000..aca715b36179 --- /dev/null +++ b/drivers/gpu/drm/tiny/ofdrm.c @@ -0,0 +1,748 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include <linux/pci.h> +#include <linux/platform_device.h> + +#include <drm/drm_aperture.h> +#include <drm/drm_atomic_state_helper.h> +#include <drm/drm_connector.h> +#include <drm/drm_damage_helper.h> +#include <drm/drm_device.h> +#include <drm/drm_drv.h> +#include <drm/drm_fb_helper.h> +#include <drm/drm_format_helper.h> +#include <drm/drm_gem_atomic_helper.h> +#include <drm/drm_gem_framebuffer_helper.h> +#include <drm/drm_gem_shmem_helper.h> +#include <drm/drm_managed.h> +#include <drm/drm_modeset_helper_vtables.h> +#include <drm/drm_probe_helper.h> +#include <drm/drm_simple_kms_helper.h> + + +#define DRIVER_NAME "ofdrm" +#define DRIVER_DESC "DRM driver for OF platform devices" +#define DRIVER_DATE "20220501" +#define DRIVER_MAJOR 1 +#define DRIVER_MINOR 0 + +/* + * Assume a monitor resolution of 96 dpi to + * get a somewhat reasonable screen size. + */ +#define RES_MM(d) \ + (((d) * 254ul) / (96ul * 10ul)) + +#define OFDRM_MODE(hd, vd) \ + DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd)) + +/* + * Helpers for display nodes + */ ++static int display_get_validated_int(struct drm_device *dev, const char *name, uint32_t value)+{ + if (value > INT_MAX) { + drm_err(dev, "invalid framebuffer %s of %u\n", name, value); + return -EINVAL; + } + return (int)value; +} ++static int display_get_validated_int0(struct drm_device *dev, const char *name, uint32_t value)+{ + if (!value) { + drm_err(dev, "invalid framebuffer %s of %u\n", name, value); + return -EINVAL; + } + return display_get_validated_int(dev, name, value); +} ++static const struct drm_format_info *display_get_validated_format(struct drm_device *dev,+ u32 depth) +{ + const struct drm_format_info *info; + u32 format; + + switch (depth) { + case 8: + format = drm_mode_legacy_fb_format(8, 8); + break; + case 15: + case 16: + format = drm_mode_legacy_fb_format(16, depth); + break; + case 32: + format = drm_mode_legacy_fb_format(32, 24); + break; + default: + drm_err(dev, "unsupported framebuffer depth %u\n", depth); + return ERR_PTR(-EINVAL); + } + + info = drm_format_info(format); + if (!info) {+ drm_err(dev, "cannot find framebuffer format for depth %u\n", depth);+ return ERR_PTR(-EINVAL); + } + + return info; +} ++static int display_read_u32_of(struct drm_device *dev, struct device_node *of_node,+ const char *name, u32 *value) +{ + int ret = of_property_read_u32(of_node, name, value); + + if (ret)+ drm_err(dev, "cannot parse framebuffer %s: error %d\n", name, ret);+ return ret; +} ++static int display_get_width_of(struct drm_device *dev, struct device_node *of_node)+{ + u32 width; + int ret = display_read_u32_of(dev, of_node, "width", &width); + + if (ret) + return ret; + return display_get_validated_int0(dev, "width", width); +} ++static int display_get_height_of(struct drm_device *dev, struct device_node *of_node)+{ + u32 height; + int ret = display_read_u32_of(dev, of_node, "height", &height); + + if (ret) + return ret; + return display_get_validated_int0(dev, "height", height); +} ++static int display_get_linebytes_of(struct drm_device *dev, struct device_node *of_node)+{ + u32 linebytes;+ int ret = display_read_u32_of(dev, of_node, "linebytes", &linebytes);+ + if (ret) + return ret; + return display_get_validated_int(dev, "linebytes", linebytes); +} ++static const struct drm_format_info *display_get_format_of(struct drm_device *dev,+ struct device_node *of_node) +{ + u32 depth; + int ret = display_read_u32_of(dev, of_node, "depth", &depth); + + if (ret) + return ERR_PTR(ret); + return display_get_validated_format(dev, depth); +} ++static u64 display_get_address_of(struct drm_device *dev, struct device_node *of_node)+{ + u32 address; + int ret; + + /* + * Not all devices provide an address property, it's not + * a bug if this fails. The driver will try to find the + * framebuffer base address from the device's memory regions. + */ + ret = of_property_read_u32(of_node, "address", &address); + if (ret) + return OF_BAD_ADDR; + + return address; +} + +#if defined(CONFIG_PCI)+static struct pci_dev *display_get_pci_dev_of(struct drm_device *dev, struct device_node *of_node)+{ + const __be32 *vendor_p, *device_p; + u32 vendor, device; + struct pci_dev *pcidev; + + vendor_p = of_get_property(of_node, "vendor-id", NULL); + if (!vendor_p) + return ERR_PTR(-ENODEV); + vendor = be32_to_cpup(vendor_p); + + device_p = of_get_property(of_node, "device-id", NULL); + if (!device_p) + return ERR_PTR(-ENODEV); + device = be32_to_cpup(device_p); + + pcidev = pci_get_device(vendor, device, NULL); + if (!pcidev) + return ERR_PTR(-ENODEV); + + return pcidev; +} +#else+static struct pci_dev *display_get_pci_dev_of(struct drm_device *dev, struct device_node *of_node)+{ + return ERR_PTR(-ENODEV); +} +#endif + +/* + * Open Firmware display device + */ + +struct ofdrm_device { + struct drm_device dev; + struct platform_device *pdev; + + /* OF display settings */ + struct drm_display_mode mode; + const struct drm_format_info *format; + unsigned int pitch; + resource_size_t fb_base; + resource_size_t fb_size; + + /* memory management */ + struct resource *mem; + void __iomem *screen_base; + + /* modesetting */ + uint32_t formats[8]; + size_t nformats; + struct drm_connector connector; + struct drm_simple_display_pipe pipe; +}; + +static struct ofdrm_device *ofdrm_device_of_dev(struct drm_device *dev) +{ + return container_of(dev, struct ofdrm_device, dev); +} + +/* + * OF display settings + */ + +static void ofdrm_pci_release(void *data) +{ + struct pci_dev *pcidev = data; + + pci_disable_device(pcidev); +} ++static struct drm_display_mode ofdrm_mode(unsigned int width, unsigned int height)+{ + struct drm_display_mode mode = { OFDRM_MODE(width, height) }; + + mode.clock = mode.hdisplay * mode.vdisplay * 60 / 1000 /* kHz */; + drm_mode_set_name(&mode); + + return mode; +} ++static struct resource *ofdrm_find_fb_resource(struct ofdrm_device *odev,+ struct resource *fb_res) +{ + struct platform_device *pdev = to_platform_device(odev->dev.dev); + struct resource *res, *max_res = NULL; + u32 i; + + for (i = 0; pdev->num_resources; ++i) { + res = platform_get_resource(pdev, IORESOURCE_MEM, i); + if (!res) + break; /* all resources processed */ + if (resource_size(res) < resource_size(fb_res)) + continue; /* resource too small */ + if (fb_res->start && resource_contains(res, fb_res)) + return res; /* resource contains framebuffer */ + if (!max_res || resource_size(res) > resource_size(max_res)) + max_res = res; /* store largest resource as fallback */ + } + + return max_res; +} + +static int ofdrm_device_init_fb(struct ofdrm_device *odev) +{ + struct drm_device *dev = &odev->dev; + struct platform_device *pdev = odev->pdev; + struct device_node *of_node = pdev->dev.of_node; + int width, height, linebytes; + u64 address; + const struct drm_format_info *format; + struct pci_dev *pcidev; + struct resource *res; + int ret; + + width = display_get_width_of(dev, of_node); + if (width < 0) + return width; + height = display_get_height_of(dev, of_node); + if (height < 0) + return height; + linebytes = display_get_linebytes_of(dev, of_node); + if (linebytes < 0) + return linebytes; + format = display_get_format_of(dev, of_node); + if (IS_ERR(format)) + return PTR_ERR(format); + address = display_get_address_of(dev, of_node); + + /* + * Never use pcim_ or other managed helpers on the returned PCI + * device. Otherwise, probing the native driver will fail for + * resource conflicts. PCI-device management has to be tied to + * the lifetime of the platform device until the native driver + * takes over. + */ + pcidev = display_get_pci_dev_of(dev, of_node); + if (!IS_ERR(pcidev)) { + ret = pci_enable_device(pcidev); + if (drm_WARN(dev, ret, "pci_enable_device(%s) failed: %d\n", + dev_name(&pcidev->dev), ret)) + return ret;+ ret = devm_add_action_or_reset(&pdev->dev, ofdrm_pci_release, pcidev);+ if (ret) + return ret; + } + + odev->mode = ofdrm_mode(width, height); + odev->format = format; + + if (linebytes) + odev->pitch = linebytes; + else + odev->pitch = width * format->cpp[0]; + + odev->fb_size = odev->pitch * height; + + /*+ * Try to figure out the address of the framebuffer. Unfortunately, Open + * Firmware doesn't provide a standard way to do so. All we can do is a+ * dodgy heuristic that happens to work in practice.This isn't quite true: there is a Forth value named "frame-buffer-adr" which should be set to the physical screen base address for PCI and non-PCI cards. It is mentioned in both the IEEE-1275 specification (page 32) and according to OpenBIOS is also referenced by BootX: https://mail.coreboot.org/pipermail/openbios/2011-August/006617.html.
I briefly looked at the patch and the spec document, but it looks like this is only for OF's Forth interface. (?) The driver is build on top of device-tree values.
+ * On most machines, the "address" property contains what we need, though + * not on Matrox cards found in IBM machines. What appears to give good + * results is to go through the PCI ranges and pick one that encloses the+ * "address" property. If none match, we pick the largest. + */In my experience so far "frame-buffer-adr" is the definitive way to get the screen physical address, however you'll need to call the CIF interface in order to get the value. The cases where I've seen an "address" property in the display node is when the display has also been mapped to a virtual address, which may or may not be the same as the physical address. I suspect this optional virtual mapping may not be present by the time the ofdrm driver loads?
It's all physical addresses.At least on qemu's emulation, there's no 'frame-buffer-addr' device-tree value. Or is it a Sparc thing?
Best regards Thomas -- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev
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