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References: <20231029194607.379459-1-suijingfeng@loongson.cn> <20231029194607.379459-2-suijingfeng@loongson.cn>
In-Reply-To: <20231029194607.379459-2-suijingfeng@loongson.cn>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Date:   Mon, 30 Oct 2023 00:59:22 +0200
Message-ID: <CAA8EJprALc_bWSsGvGmChupcHOWRCDO+G7M51gxFU-WuUAUDOg@mail.gmail.com>
Subject: Re: [PATCH 1/8] drm/loongson: Introduce a minimal support for
 Loongson VBIOS
To:     Sui Jingfeng <suijingfeng@loongson.cn>
Cc:     Maxime Ripard <mripard@kernel.org>,
        Thomas Zimmermann <tzimmermann@suse.de>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Sun, 29 Oct 2023 at 21:46, Sui Jingfeng <suijingfeng@loongson.cn> wrote:
>
> Because some boards are equipped with non-transparent display bridges,
> which need the VBIOS to provided parameters.
>
> Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
> ---
>  drivers/gpu/drm/loongson/Makefile          |   3 +-
>  drivers/gpu/drm/loongson/loongson_device.c |   4 +
>  drivers/gpu/drm/loongson/loongson_vbios.c  | 420 +++++++++++++++++++++
>  drivers/gpu/drm/loongson/loongson_vbios.h  |  59 +++
>  drivers/gpu/drm/loongson/lsdc_drv.c        |   4 +
>  drivers/gpu/drm/loongson/lsdc_drv.h        |   8 +
>  6 files changed, 497 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/loongson/loongson_vbios.c
>  create mode 100644 drivers/gpu/drm/loongson/loongson_vbios.h
>
> diff --git a/drivers/gpu/drm/loongson/Makefile b/drivers/gpu/drm/loongson/Makefile
> index 91e72bd900c1..bef00b2c5569 100644
> --- a/drivers/gpu/drm/loongson/Makefile
> +++ b/drivers/gpu/drm/loongson/Makefile
> @@ -17,6 +17,7 @@ loongson-y := \
>         lsdc_ttm.o
>
>  loongson-y += loongson_device.o \
> -             loongson_module.o
> +             loongson_module.o \
> +             loongson_vbios.o
>
>  obj-$(CONFIG_DRM_LOONGSON) += loongson.o
> diff --git a/drivers/gpu/drm/loongson/loongson_device.c b/drivers/gpu/drm/loongson/loongson_device.c
> index 9986c8a2a255..64096ad5466e 100644
> --- a/drivers/gpu/drm/loongson/loongson_device.c
> +++ b/drivers/gpu/drm/loongson/loongson_device.c
> @@ -7,6 +7,8 @@
>
>  #include "lsdc_drv.h"
>
> +extern struct loongson_vbios __loongson_vbios;

Usually names with two underscores in front of them are reserved for
the compiler internals or low level stuff.

> +
>  static const struct lsdc_kms_funcs ls7a1000_kms_funcs = {
>         .create_i2c = lsdc_create_i2c_chan,
>         .irq_handler = ls7a1000_dc_irq_handler,
> @@ -53,6 +55,7 @@ static const struct loongson_gfx_desc ls7a1000_gfx = {
>                         .reg_size = 8,
>                 },
>         },
> +       .vbios = &__loongson_vbios,
>         .chip_id = CHIP_LS7A1000,
>         .model = "LS7A1000 bridge chipset",
>  };
> @@ -85,6 +88,7 @@ static const struct loongson_gfx_desc ls7a2000_gfx = {
>                         .reg_size = 8,
>                 },
>         },
> +       .vbios = &__loongson_vbios,
>         .chip_id = CHIP_LS7A2000,
>         .model = "LS7A2000 bridge chipset",
>  };
> diff --git a/drivers/gpu/drm/loongson/loongson_vbios.c b/drivers/gpu/drm/loongson/loongson_vbios.c
> new file mode 100644
> index 000000000000..dc304018779e
> --- /dev/null
> +++ b/drivers/gpu/drm/loongson/loongson_vbios.c
> @@ -0,0 +1,420 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2023 Loongson Technology Corporation Limited
> + */
> +
> +#include <drm/drm_device.h>
> +#include <drm/drm_managed.h>
> +
> +#include "loongson_vbios.h"
> +#include "lsdc_drv.h"
> +
> +#define LOONGSON_VBIOS_HEADER_STR       "Loongson-VBIOS"
> +/* Legacy VBIOS is stored at offset 0 */
> +#define LOONGSON_VBIOS_LEGACY_OFFSET     0
> +/* The size of legacy VBIOS is 1 KiB */
> +#define LOONGSON_VBIOS_LEGACY_SIZE       0x000400
> +
> +/* Data Control Block of Newer version of the VBIOS started at here */
> +#define LOONGSON_VBIOS_DCB_OFFSET        0x006000
> +/* The last 1 MiB of the VRAM contains the raw VBIOS data */
> +#define LOONGSON_VBIOS_BLOCK_OFFSET      0x100000
> +/* Only 256KB of the 1 MiB are used for now */
> +#define LOONGSON_VBIOS_BLOCK_SIZE        0x040000
> +
> +struct loongson_vbios __loongson_vbios;
> +
> +/*
> + * vbios data control block is a kind of metadata, which is used to index
> + * real hardware device data block.
> + */
> +struct loongson_vbios_dcb {
> +       u16 type;    /* what is it */
> +       u8 version;  /* version of it, useless */
> +       u8 id;       /* index (usually same with the display pipe) of the hardware */
> +       u32 offset;  /* the offset of the real data */
> +       u32 size;    /* the size of the real data */
> +       u64 ext0;    /* for extension purpose */
> +       u64 ext1;    /* extra space reserved for future use */
> +} __packed;
> +
> +/*
> + * Loongson-VBIOS Data Block Layout
> + *
> + *
> + *         _____________________   0x00000
> + *        |_____________________|
> + *        |                     |  [0x0000, 0x0400) : legacy vbios storage
> + *        |    Not Used Yet     |
> + *        |                     |
> + *        |---------------------|<------- 0x6000
> + *   +----|        DCB 0        |
> + *   |    |---------------------|
> + *   |    |        DCB 1        |
> + *   |    |---------------------|      Format of Data Control Blocks
> + *   |    | One by one, packed  |            +------------+
> + *   |    |---------------------|            |  u16 type  |
> + *   |    |        DCB N        |----+       |            |
> + *   |    |---------------------|    |       +------------+
> + *   |    |          .          |    |       | u8 version |
> + *   |    |          .          |    |       |  u8 index  |
> + *   |    |          .          |    |       +------------+
> + *   |    |---------------------|    |       |            |
> + *   |    |        DCB end      |    |       | u32 offset |
> + *   |    |---------------------|    |   +-------         |
> + *   |    |                     |    |   |   |            |
> + *   |    |_____________________|    |   |   +------------+
> + *   |    |_____________________|    |   |   |            |
> + *   |    |                     |    |   |   |  u32 size  |
> + *   +--->|  vbios header info  |    |   |   |         -------+
> + *        |_____________________|    |   |   |            |   |
> + *        |          .          |    |   |   +------------+   |
> + *        |          .          |    |   |   |  useless   |   |
> + *        |          .          |    |   |   |  members   |   |
> + *        |_____________________|    |   |   +------------+   |
> + *        |                     |    |   |                    |
> + *        |    encoders info    |<---+   |                    |
> + *        |_____________________|        |                    |
> + *        |                     |     ___|                    |
> + *        |_____________________|____/                        |
> + *        |                     |                             |
> + *        |      Something      |                             |
> + *        |_____________________|_________________            |
> + *        |                     |             |               |
> + *        |        EDID         |             |<--------------+
> + *        |_____________________|_____________|___
> + *        |                     |
> + *        |                     |    Contents of those device specific data
> + *        |  GPU specific info  |    block are implement-defined and version
> + *        |                     |    dependent :0
> + *        |_____________________|
> + *        /          .          /
> + *        /          .          /
> + *        /          .          /
> + *        |_____________________|  0x040000
> + *
> + */
> +
> +enum loongson_vbios_dcb_type {
> +       LV_DCB_HEADER = 0,
> +       LV_DCB_CRTC = 1,
> +       LV_DCB_ENCODER = 2,
> +       LV_DCB_CONNECTOR = 3,
> +       LV_DCB_I2C = 4,
> +       LV_DCB_PWM = 5,
> +       LV_DCB_GPIO = 6,
> +       LV_DCB_BACKLIGHT = 7,
> +       LV_DCB_FAN = 8,
> +       LV_DCB_IRQ = 9,
> +       LV_DCB_ENCODER_CFG = 10,
> +       LV_DCB_ENCODER_RES = 11,
> +       LV_DCB_GPU = 12,
> +       LV_DCB_UNKNOWN = 13,
> +       LV_DCB_END = 0xffff,
> +};
> +
> +struct loongson_vbios_header {
> +       char header[16];
> +       u32 version_major;

Please specify whether this is BE or LE. (__be32 or __le32). Usually
we use le32_to_cpu / be32_to_cpu helpers to access external data.

> +       u32 version_minor;
> +       char information[20];
> +       u32 num_crtc;
> +       u32 crtc_offset;
> +       u32 num_connector;
> +       u32 connector_offset;
> +       u32 num_encoder;
> +       u32 encoder_offset;
> +} __packed;
> +
> +struct loongson_vbios_encoder {
> +       u32 feature;
> +       u32 i2c_id;
> +       u32 connector_id;
> +       u32 type;
> +       u32 config_method;
> +       u32 chip_id;
> +       u8 chip_addr;
> +} __packed;
> +
> +struct loongson_vbios_connector {
> +       u32 feature;
> +       u32 i2c_id;
> +       u8  edid[256];
> +       u32 type;
> +       u32 hotplug_method;
> +       u32 edid_method;
> +       u32 hpd_int_gpio;
> +       u32 gpio_place;
> +} __packed;
> +
> +/*
> + * A list node which contains the information about the device specific data
> + * block, the device here refer to the property or topology of hardware
> + * configuration, such as external display bridges, HDP GPIO, connectors etc.
> + */
> +struct loongson_vbios_node {
> +       struct list_head head;
> +
> +       /* @type: the type of the data. For search */
> +       u32 type;
> +       /* @id: the index(display pipe) of the data belong to. For search */
> +       u32 id;
> +       /*
> +        * @data: point to the device specific data block, such as external
> +        * encoders name and it's i2c device address, hpd gpio resource etc.
> +        */
> +       const void *data;
> +       /*
> +        * The size of the data.
> +        */
> +       u32 size;
> +};
> +
> +/*
> + * The returned pointer is actually point to &__loongson_vbios, but this
> + * function is only intended to provide READ-ONLY access. As our vbios is
> + * only be able to pass(provide) parameters, it is not executable and outside
> + * should not modify it.
> + */
> +const struct loongson_vbios *to_loongson_vbios(struct drm_device *ddev)
> +{
> +       struct lsdc_device *ldev = to_lsdc(ddev);
> +       const struct loongson_gfx_desc *gfx = to_loongson_gfx(ldev->descp);
> +
> +       return gfx->vbios;
> +}
> +
> +static bool loongson_vbios_is_valid(const struct loongson_vbios *vbios)
> +{
> +       char header[32];
> +
> +       memcpy(header, vbios->raw_data, sizeof(header));
> +
> +       if (strcmp(header, LOONGSON_VBIOS_HEADER_STR))
> +               return false;
> +
> +       return true;
> +}
> +
> +/*
> + * The VBIOS blob is stored at the last 1 MiB of the VRAM, no SPI flush or

flash?

> + * EEPROM is needed. Platform BIOS is responsible for store this VBIOS blob

storing

> + * data at right position on per boot time.
> + */
> +static int loongson_vbios_construct(struct drm_device *ddev,
> +                                   struct loongson_vbios *vbios)
> +{
> +       struct lsdc_device *ldev = to_lsdc(ddev);
> +       u64 vram_end = ldev->vram_base + ldev->vram_size;
> +       u64 vbios_start = vram_end - LOONGSON_VBIOS_BLOCK_OFFSET;
> +       void __iomem *ptr;
> +
> +       vbios->raw_data = kzalloc(LOONGSON_VBIOS_BLOCK_SIZE, GFP_KERNEL);
> +       if (!vbios->raw_data)
> +               return -ENOMEM;
> +
> +       ptr = ioremap(vbios_start, LOONGSON_VBIOS_BLOCK_SIZE);
> +       if (!ptr) {
> +               drm_err(ddev, "Map VBIOS region failed\n");
> +               return -ENOMEM;
> +       }
> +
> +       memcpy_fromio(vbios->raw_data, ptr, LOONGSON_VBIOS_BLOCK_SIZE);
> +
> +       iounmap(ptr);
> +
> +       INIT_LIST_HEAD(&vbios->list);
> +       vbios->ddev = ddev;
> +
> +       return 0;
> +}
> +
> +static void loongson_vbios_destruct(struct drm_device *ddev, void *data)

destroy or free. Also you can use drmm_ functions to make destructor
unnecessary.

> +{
> +       struct loongson_vbios *vbios = (struct loongson_vbios *)data;
> +       struct loongson_vbios_node *node;
> +       struct loongson_vbios_node *tmp;
> +
> +       list_for_each_entry_safe(node, tmp, &vbios->list, head) {
> +               list_del(&node->head);
> +               kfree(node);
> +       }
> +
> +       kfree(vbios->raw_data);
> +       vbios->raw_data = NULL;
> +}
> +
> +static void loongson_vbios_print_dcb(struct drm_device *ddev,
> +                                    struct loongson_vbios_dcb *dcb)
> +{
> +       drm_info(ddev, "type: %u, Offset: %u, Size: %u, version: %u, ID: %u\n",
> +                dcb->type, dcb->offset, dcb->size, dcb->version, dcb->id);
> +}
> +
> +/*
> + * Process the data control block, establish a list for later searching.
> + * returns the number of data control block. Generally, loongson vbios
> + * has only 10 DCB or so.
> + */
> +static int loongson_vbios_process_dcb(struct loongson_vbios *vbios,
> +                                     bool verbose)
> +{
> +       struct drm_device *ddev = vbios->ddev;
> +       void *base = vbios->raw_data;
> +       int count = 0;
> +       struct loongson_vbios_dcb *dcb;
> +
> +       dcb = (struct loongson_vbios_dcb *)(base + LOONGSON_VBIOS_DCB_OFFSET);
> +
> +       while (dcb->type != LV_DCB_END) {
> +               struct loongson_vbios_node *node;
> +
> +               node = kzalloc(sizeof(*node), GFP_KERNEL);
> +               if (!node)
> +                       return -ENOMEM;
> +
> +               node->type = dcb->type;
> +               node->id = dcb->id;
> +               node->data = base + dcb->offset;
> +               node->size = dcb->size;
> +
> +               list_add_tail(&node->head, &vbios->list);
> +
> +               if (verbose)
> +                       loongson_vbios_print_dcb(ddev, dcb);
> +
> +               ++dcb;
> +
> +               if (++count > 1024) {
> +                       drm_err(ddev, "Unlikely, DCB is too much\n");
> +                       break;
> +               }
> +       }
> +
> +       return count;
> +}
> +
> +static const struct loongson_vbios_node *
> +loongson_vbios_get_node(struct drm_device *ddev, u32 type, u32 id)
> +{
> +       const struct loongson_vbios *vbios = to_loongson_vbios(ddev);
> +       struct loongson_vbios_node *np;
> +
> +       if (!vbios)
> +               return NULL;
> +
> +       list_for_each_entry(np, &vbios->list, head) {
> +               if (np->type == type && np->id == id)
> +                       return np;
> +       }
> +
> +       return NULL;
> +}
> +
> +bool loongson_vbios_query_encoder_info(struct drm_device *ddev,
> +                                      u32 pipe,
> +                                      u32 *type,
> +                                      enum loongson_vbios_encoder_name *name,
> +                                      u8 *i2c_addr)
> +{
> +       const struct loongson_vbios_encoder *vencoder;
> +       const struct loongson_vbios_node *np;
> +
> +       np = loongson_vbios_get_node(ddev, LV_DCB_ENCODER, pipe);
> +       if (!np)
> +               return false;
> +
> +       if (np->size != sizeof(*vencoder))
> +               WARN_ON(1);
> +
> +       vencoder = (const struct loongson_vbios_encoder *)np->data;
> +
> +       if (type)
> +               *type = vencoder->type;
> +
> +       if (name)
> +               *name = vencoder->chip_id;
> +
> +       /* i2c address, as a slave device */
> +       if (i2c_addr)
> +               *i2c_addr = vencoder->chip_addr;
> +
> +       return true;
> +}
> +
> +bool loongson_vbios_query_connector_info(struct drm_device *ddev,
> +                                        u32 pipe,
> +                                        u32 *connector_type,
> +                                        u32 *hpd_method,
> +                                        u32 *int_gpio,
> +                                        u8 *edid_blob)
> +{
> +       const struct loongson_vbios_connector *vconnector;
> +       const struct loongson_vbios_node *np;
> +
> +       np = loongson_vbios_get_node(ddev, LV_DCB_CONNECTOR, pipe);
> +       if (!np)
> +               return false;
> +
> +       if (np->size != sizeof(*vconnector))
> +               WARN_ON(1);
> +
> +       vconnector = (const struct loongson_vbios_connector *)np->data;
> +
> +       if (connector_type)
> +               *connector_type = vconnector->type;
> +
> +       if (edid_blob)
> +               memcpy(edid_blob, vconnector->edid, 256);
> +
> +       if (int_gpio)
> +               *int_gpio = vconnector->hpd_int_gpio;
> +
> +       return true;
> +}
> +
> +static void loongson_vbios_acquire_version(struct drm_device *ddev,
> +                                          struct loongson_vbios *vbios)
> +{
> +       struct loongson_vbios_header *vh;
> +
> +       vh = (struct loongson_vbios_header *)vbios->raw_data;
> +
> +       vbios->version_major = vh->version_major;
> +       vbios->version_minor = vh->version_minor;
> +
> +       drm_info(ddev, "Loongson VBIOS version: %u.%u\n",
> +                vh->version_major, vh->version_minor);
> +}
> +
> +int loongson_vbios_init(struct drm_device *ddev)
> +{
> +       struct loongson_vbios *vbios = &__loongson_vbios;
> +       int ret;
> +       int num;
> +
> +       ret = loongson_vbios_construct(ddev, vbios);
> +       if (ret)
> +               return ret;
> +
> +       ret = drmm_add_action_or_reset(ddev, loongson_vbios_destruct, vbios);
> +       if (ret)
> +               return ret;
> +
> +       if (!loongson_vbios_is_valid(vbios)) {
> +               drm_err(ddev, "Loongson VBIOS: header is invalid\n");
> +               return -EINVAL;
> +       }
> +
> +       loongson_vbios_acquire_version(ddev, vbios);

get_version.

> +
> +       num = loongson_vbios_process_dcb(vbios, false);
> +       if (num <= 0) {
> +               drm_err(ddev, "Loongson VBIOS: Process DCB failed\n");
> +               return -EINVAL;
> +       }
> +
> +       drm_info(ddev, "Loongson VBIOS: has %d DCBs\n", num);
> +
> +       return 0;
> +}
> diff --git a/drivers/gpu/drm/loongson/loongson_vbios.h b/drivers/gpu/drm/loongson/loongson_vbios.h
> new file mode 100644
> index 000000000000..66fb43b3609e
> --- /dev/null
> +++ b/drivers/gpu/drm/loongson/loongson_vbios.h
> @@ -0,0 +1,59 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * Copyright (C) 2023 Loongson Technology Corporation Limited
> + */
> +
> +#ifndef __LOONGSON_VBIOS_H__
> +#define __LOONGSON_VBIOS_H__
> +
> +#include <drm/drm_device.h>
> +
> +struct loongson_vbios {
> +       struct list_head list;
> +       void *raw_data;
> +       struct drm_device *ddev;
> +       u32 version_major;
> +       u32 version_minor;
> +};
> +
> +enum loongson_vbios_encoder_name {
> +       ENCODER_CHIP_UNKNOWN = 0x00,
> +       ENCODER_CHIP_INTERNAL_VGA = 0x01,
> +       ENCODER_CHIP_INTERNAL_HDMI = 0x02,
> +       ENCODER_CHIP_CH7055 = 0x10,
> +       ENCODER_CHIP_ADV7125 = 0x11,
> +       ENCODER_CHIP_TFP410 = 0x20,
> +       ENCODER_CHIP_IT66121 = 0x30,
> +       ENCODER_CHIP_SIL9022 = 0x31,
> +       ENCODER_CHIP_LT8618 = 0x32,
> +       ENCODER_CHIP_MS7210 = 0x33,
> +       ENCODER_CHIP_NCS8805 = 0x40,
> +       ENCODER_CHIP_LT9721 = 0x42,
> +       ENCODER_CHIP_LT6711 = 0x43,
> +       ENCODER_CHIP_LT8619 = 0x50,
> +};
> +
> +enum loongson_vbios_hotplug_method {
> +       LV_HPD_DISABLED = 0,
> +       LV_HPD_POLLING = 1,
> +       LV_HPD_IRQ = 2,
> +};
> +
> +const struct loongson_vbios *to_loongson_vbios(struct drm_device *ddev);
> +
> +bool loongson_vbios_query_encoder_info(struct drm_device *ddev,
> +                                      u32 pipe,
> +                                      u32 *type,
> +                                      enum loongson_vbios_encoder_name *name,
> +                                      u8 *i2c_addr);
> +
> +bool loongson_vbios_query_connector_info(struct drm_device *ddev,
> +                                        u32 pipe,
> +                                        u32 *connector_type,
> +                                        u32 *hpd_method,
> +                                        u32 *int_gpio,
> +                                        u8 *edid_blob);
> +
> +int loongson_vbios_init(struct drm_device *ddev);
> +
> +#endif
> diff --git a/drivers/gpu/drm/loongson/lsdc_drv.c b/drivers/gpu/drm/loongson/lsdc_drv.c
> index 89ccc0c43169..aebb200fa567 100644
> --- a/drivers/gpu/drm/loongson/lsdc_drv.c
> +++ b/drivers/gpu/drm/loongson/lsdc_drv.c
> @@ -213,6 +213,10 @@ lsdc_create_device(struct pci_dev *pdev,
>                 return ERR_PTR(ret);
>         }
>
> +       ret = loongson_vbios_init(ddev);
> +       if (ret)
> +               drm_info(ddev, "No VBIOS support\n");
> +
>         ret = drm_aperture_remove_conflicting_framebuffers(ldev->vram_base,
>                                                            ldev->vram_size,
>                                                            driver);
> diff --git a/drivers/gpu/drm/loongson/lsdc_drv.h b/drivers/gpu/drm/loongson/lsdc_drv.h
> index fbf2d760ef27..335953c988d1 100644
> --- a/drivers/gpu/drm/loongson/lsdc_drv.h
> +++ b/drivers/gpu/drm/loongson/lsdc_drv.h
> @@ -16,6 +16,7 @@
>  #include <drm/drm_plane.h>
>  #include <drm/ttm/ttm_device.h>
>
> +#include "loongson_vbios.h"
>  #include "lsdc_i2c.h"
>  #include "lsdc_irq.h"
>  #include "lsdc_gfxpll.h"
> @@ -85,6 +86,13 @@ struct loongson_gfx_desc {
>                 u32 reg_size;
>         } pixpll[LSDC_NUM_CRTC];
>
> +       /*
> +        * @vbios: Provide information about the output configuration,
> +        * and provide information about dynamic features which cannot
> +        * be detected(determined) with the chip_id.
> +        */
> +       const struct loongson_vbios *vbios;
> +
>         enum loongson_chip_id chip_id;
>         char model[64];
>  };
> --
> 2.34.1
>


-- 
With best wishes
Dmitry