diff options
Diffstat (limited to 'drivers/firmware/coreboot/framebuffer-coreboot.c')
| -rw-r--r-- | drivers/firmware/coreboot/framebuffer-coreboot.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/drivers/firmware/coreboot/framebuffer-coreboot.c b/drivers/firmware/coreboot/framebuffer-coreboot.c new file mode 100644 index 000000000000..1a6d4ac6db31 --- /dev/null +++ b/drivers/firmware/coreboot/framebuffer-coreboot.c @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * framebuffer-coreboot.c + * + * Memory based framebuffer accessed through coreboot table. + * + * Copyright 2012-2013 David Herrmann <dh.herrmann@gmail.com> + * Copyright 2017 Google Inc. + * Copyright 2017 Samuel Holland <samuel@sholland.org> + */ + +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/mm.h> +#include <linux/device-id/coreboot.h> +#include <linux/module.h> +#include <linux/pci.h> +#include <linux/platform_data/simplefb.h> +#include <linux/platform_device.h> +#include <linux/sysfb.h> + +#include "coreboot_table.h" + +#if defined(CONFIG_PCI) +static bool framebuffer_pci_dev_is_enabled(struct pci_dev *pdev) +{ + /* + * TODO: Try to integrate this code into the PCI subsystem + */ + int ret; + u16 command; + + ret = pci_read_config_word(pdev, PCI_COMMAND, &command); + if (ret != PCIBIOS_SUCCESSFUL) + return false; + if (!(command & PCI_COMMAND_MEMORY)) + return false; + return true; +} + +static struct pci_dev *framebuffer_parent_pci_dev(struct resource *res) +{ + struct pci_dev *pdev = NULL; + const struct resource *r = NULL; + + while (!r && (pdev = pci_get_base_class(PCI_BASE_CLASS_DISPLAY, pdev))) + r = pci_find_resource(pdev, res); + + if (!r || !pdev) + return NULL; /* not found; not an error */ + + if (!framebuffer_pci_dev_is_enabled(pdev)) { + pci_dev_put(pdev); + return ERR_PTR(-ENODEV); + } + + return pdev; +} +#else +static struct pci_dev *framebuffer_parent_pci_dev(struct resource *res) +{ + return NULL; +} +#endif + +static struct device *framebuffer_parent_dev(struct resource *res) +{ + struct pci_dev *pdev; + + pdev = framebuffer_parent_pci_dev(res); + if (IS_ERR(pdev)) + return ERR_CAST(pdev); + else if (pdev) + return &pdev->dev; + + return NULL; +} + +static int framebuffer_probe(struct coreboot_device *dev) +{ + struct lb_framebuffer *fb = &dev->framebuffer; + struct device *parent; + struct platform_device *pdev; + struct resource res; + int ret; +#if !IS_ENABLED(CONFIG_DRM_COREBOOTDRM) + struct simplefb_platform_data pdata = { + .width = fb->x_resolution, + .height = fb->y_resolution, + .stride = fb->bytes_per_line, + .format = NULL, + }; + int i; + static const struct simplefb_format formats[] = SIMPLEFB_FORMATS; +#endif + + /* + * On coreboot systems, the advertised LB_TAG_FRAMEBUFFER entry + * in the coreboot table should only be used if the payload did + * not pass a framebuffer information to the Linux kernel. + * + * If the global screen_info data has been filled, the Generic + * System Framebuffers (sysfb) will already register a platform + * device and pass that screen_info as platform_data to a driver + * that can scan-out using the system provided framebuffer. + */ + if (sysfb_handles_screen_info()) + return -ENODEV; + + if (!fb->physical_address) + return -ENODEV; + + res = DEFINE_RES_MEM(fb->physical_address, + PAGE_ALIGN(fb->y_resolution * fb->bytes_per_line)); + if (res.end <= res.start) + return -EINVAL; + + parent = framebuffer_parent_dev(&res); + if (IS_ERR(parent)) + return PTR_ERR(parent); + +#if IS_ENABLED(CONFIG_DRM_COREBOOTDRM) + pdev = platform_device_register_resndata(parent, "coreboot-framebuffer", 0, + &res, 1, fb, fb->size); + if (IS_ERR(pdev)) { + pr_warn("coreboot: could not register framebuffer\n"); + ret = PTR_ERR(pdev); + goto out_put_device_parent; + } +#else + /* + * FIXME: Coreboot systems should use a driver that binds to + * coreboot-framebuffer devices. Remove support for + * simple-framebuffer at some point. + */ + for (i = 0; i < ARRAY_SIZE(formats); ++i) { + if (fb->bits_per_pixel == formats[i].bits_per_pixel && + fb->red_mask_pos == formats[i].red.offset && + fb->red_mask_size == formats[i].red.length && + fb->green_mask_pos == formats[i].green.offset && + fb->green_mask_size == formats[i].green.length && + fb->blue_mask_pos == formats[i].blue.offset && + fb->blue_mask_size == formats[i].blue.length) + pdata.format = formats[i].name; + } + if (!pdata.format) { + ret = -ENODEV; + goto out_put_device_parent; + } + + pdev = platform_device_register_resndata(parent, + "simple-framebuffer", 0, + &res, 1, &pdata, + sizeof(pdata)); + if (IS_ERR(pdev)) { + ret = PTR_ERR(pdev); + pr_warn("coreboot: could not register framebuffer\n"); + goto out_put_device_parent; + } +#endif + + ret = 0; + +out_put_device_parent: + if (parent) + put_device(parent); + return ret; +} + +static const struct coreboot_device_id framebuffer_ids[] = { + { .tag = CB_TAG_FRAMEBUFFER }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(coreboot, framebuffer_ids); + +static struct coreboot_driver framebuffer_driver = { + .probe = framebuffer_probe, + .drv = { + .name = "framebuffer", + }, + .id_table = framebuffer_ids, +}; +module_coreboot_driver(framebuffer_driver); + +MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>"); +MODULE_DESCRIPTION("Memory based framebuffer accessed through coreboot table"); +MODULE_LICENSE("GPL"); |