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    SubjectRe: [PATCH 3/6] drm/bridge: Add SPI DBI host driver
    Hi Paul,

    Thank you for the patch.

    On Mon, Jul 27, 2020 at 06:46:10PM +0200, Paul Cercueil wrote:
    > This driver will register a DBI host driver for panels connected over
    > SPI.
    >
    > DBI types c1 and c3 are supported. C1 is a SPI protocol with 9 bits per
    > word, with the data/command information in the 9th (MSB) bit. C3 is a
    > SPI protocol with 8 bits per word, with the data/command information
    > carried by a separate GPIO.
    >
    > Signed-off-by: Paul Cercueil <paul@crapouillou.net>
    > ---
    > drivers/gpu/drm/bridge/Kconfig | 8 +
    > drivers/gpu/drm/bridge/Makefile | 1 +
    > drivers/gpu/drm/bridge/dbi-spi.c | 261 +++++++++++++++++++++++++++++++
    > 3 files changed, 270 insertions(+)
    > create mode 100644 drivers/gpu/drm/bridge/dbi-spi.c
    >
    > diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
    > index c7f0dacfb57a..ed38366847c1 100644
    > --- a/drivers/gpu/drm/bridge/Kconfig
    > +++ b/drivers/gpu/drm/bridge/Kconfig
    > @@ -219,6 +219,14 @@ config DRM_TI_TPD12S015
    > Texas Instruments TPD12S015 HDMI level shifter and ESD protection
    > driver.
    >
    > +config DRM_MIPI_DBI_SPI
    > + tristate "SPI host support for MIPI DBI"
    > + depends on OF && SPI
    > + select DRM_MIPI_DSI
    > + select DRM_MIPI_DBI
    > + help
    > + Driver to support DBI over SPI.
    > +
    > source "drivers/gpu/drm/bridge/analogix/Kconfig"
    >
    > source "drivers/gpu/drm/bridge/adv7511/Kconfig"
    > diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
    > index 7d7c123a95e4..c2c522c2774f 100644
    > --- a/drivers/gpu/drm/bridge/Makefile
    > +++ b/drivers/gpu/drm/bridge/Makefile
    > @@ -20,6 +20,7 @@ obj-$(CONFIG_DRM_I2C_ADV7511) += adv7511/
    > obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
    > obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
    > obj-$(CONFIG_DRM_TI_TPD12S015) += ti-tpd12s015.o
    > +obj-$(CONFIG_DRM_MIPI_DBI_SPI) += dbi-spi.o
    > obj-$(CONFIG_DRM_NWL_MIPI_DSI) += nwl-dsi.o
    >
    > obj-y += analogix/
    > diff --git a/drivers/gpu/drm/bridge/dbi-spi.c b/drivers/gpu/drm/bridge/dbi-spi.c
    > new file mode 100644
    > index 000000000000..1060b8f95fba
    > --- /dev/null
    > +++ b/drivers/gpu/drm/bridge/dbi-spi.c
    > @@ -0,0 +1,261 @@
    > +// SPDX-License-Identifier: GPL-2.0-or-later
    > +/*
    > + * MIPI Display Bus Interface (DBI) SPI support
    > + *
    > + * Copyright 2016 Noralf Trønnes
    > + * Copyright 2020 Paul Cercueil <paul@crapouillou.net>
    > + */
    > +
    > +#include <linux/gpio/consumer.h>
    > +#include <linux/module.h>
    > +#include <linux/spi/spi.h>
    > +
    > +#include <drm/drm_mipi_dbi.h>
    > +#include <drm/drm_mipi_dsi.h>
    > +
    > +#include <video/mipi_display.h>
    > +
    > +struct dbi_spi {
    > + struct mipi_dsi_host host;
    > + struct mipi_dsi_host_ops host_ops;
    > +
    > + struct spi_device *spi;
    > + struct gpio_desc *dc;
    > + struct mutex cmdlock;
    > +
    > + unsigned int current_bus_type;
    > +
    > + /**
    > + * @tx_buf9: Buffer used for Option 1 9-bit conversion
    > + */
    > + void *tx_buf9;
    > +
    > + /**
    > + * @tx_buf9_len: Size of tx_buf9.
    > + */
    > + size_t tx_buf9_len;
    > +};
    > +
    > +static inline struct dbi_spi *host_to_dbi_spi(struct mipi_dsi_host *host)
    > +{
    > + return container_of(host, struct dbi_spi, host);
    > +}
    > +
    > +static ssize_t dbi_spi1_transfer(struct mipi_dsi_host *host,
    > + const struct mipi_dsi_msg *msg)
    > +{
    > + struct dbi_spi *dbi = host_to_dbi_spi(host);
    > + struct spi_device *spi = dbi->spi;
    > + struct spi_transfer tr = {
    > + .bits_per_word = 9,
    > + };
    > + const u8 *src8 = msg->tx_buf;
    > + struct spi_message m;
    > + size_t max_chunk, chunk;
    > + size_t len = msg->tx_len;
    > + bool cmd_byte = true;
    > + unsigned int i;
    > + u16 *dst16;
    > + int ret;
    > +
    > + tr.speed_hz = mipi_dbi_spi_cmd_max_speed(spi, len);
    > + dst16 = dbi->tx_buf9;
    > +
    > + max_chunk = min(dbi->tx_buf9_len / 2, len);
    > +
    > + spi_message_init_with_transfers(&m, &tr, 1);
    > + tr.tx_buf = dst16;
    > +
    > + while (len) {
    > + chunk = min(len, max_chunk);
    > +
    > + for (i = 0; i < chunk; i++) {
    > + dst16[i] = *src8++;
    > +
    > + /* Bit 9: 0 means command, 1 means data */
    > + if (!cmd_byte)
    > + dst16[i] |= BIT(9);
    > +
    > + cmd_byte = false;
    > + }
    > +
    > + tr.len = chunk * 2;
    > + len -= chunk;
    > +
    > + ret = spi_sync(spi, &m);
    > + if (ret)
    > + return ret;
    > + }
    > +
    > + return 0;
    > +}
    > +
    > +static ssize_t dbi_spi3_transfer(struct mipi_dsi_host *host,
    > + const struct mipi_dsi_msg *msg)
    > +{
    > + struct dbi_spi *dbi = host_to_dbi_spi(host);
    > + struct spi_device *spi = dbi->spi;
    > + const u8 *buf = msg->tx_buf;
    > + unsigned int bpw = 8;
    > + u32 speed_hz;
    > + ssize_t ret;
    > +
    > + /* for now we only support sending messages, not receiving */
    > + if (msg->rx_len)
    > + return -EINVAL;
    > +
    > + gpiod_set_value_cansleep(dbi->dc, 0);
    > +
    > + speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
    > + ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, buf, 1);
    > + if (ret || msg->tx_len == 1)
    > + return ret;
    > +
    > + if (buf[0] == MIPI_DCS_WRITE_MEMORY_START)
    > + bpw = 16;
    > +
    > + gpiod_set_value_cansleep(dbi->dc, 1);
    > + speed_hz = mipi_dbi_spi_cmd_max_speed(spi, msg->tx_len - 1);
    > +
    > + ret = mipi_dbi_spi_transfer(spi, speed_hz, bpw,
    > + &buf[1], msg->tx_len - 1);
    > + if (ret)
    > + return ret;
    > +
    > + return msg->tx_len;
    > +}
    > +
    > +static ssize_t dbi_spi_transfer(struct mipi_dsi_host *host,
    > + const struct mipi_dsi_msg *msg)
    > +{
    > + struct dbi_spi *dbi = host_to_dbi_spi(host);
    > +
    > + switch (dbi->current_bus_type) {
    > + case MIPI_DEVICE_TYPE_DBI_SPI_MODE1:
    > + return dbi_spi1_transfer(host, msg);
    > + case MIPI_DEVICE_TYPE_DBI_SPI_MODE3:
    > + return dbi_spi3_transfer(host, msg);
    > + default:
    > + dev_err(&dbi->spi->dev, "Unknown transfer type\n");
    > + return -EINVAL;
    > + }
    > +}
    > +
    > +static int dbi_spi_attach(struct mipi_dsi_host *host,
    > + struct mipi_dsi_device *dsi)
    > +{
    > + struct dbi_spi *dbi = host_to_dbi_spi(host);
    > +
    > + dbi->current_bus_type = dsi->bus_type;
    > +
    > + if (dbi->current_bus_type == MIPI_DEVICE_TYPE_DBI_SPI_MODE1) {
    > + dbi->tx_buf9_len = SZ_16K;
    > +
    > + dbi->tx_buf9 = kmalloc(dbi->tx_buf9_len, GFP_KERNEL);
    > + if (!dbi->tx_buf9)
    > + return -ENOMEM;
    > + }
    > +
    > + return 0;
    > +}
    > +
    > +static int dbi_spi_detach(struct mipi_dsi_host *host,
    > + struct mipi_dsi_device *dsi)
    > +{
    > + struct dbi_spi *dbi = host_to_dbi_spi(host);
    > +
    > + kfree(dbi->tx_buf9);
    > + dbi->tx_buf9_len = 0;
    > +
    > + return 0; /* Nothing to do */
    > +}
    > +
    > +static void dbi_spi_host_unregister(void *d)
    > +{
    > + mipi_dsi_host_unregister(d);
    > +}
    > +
    > +static int dbi_spi_probe(struct spi_device *spi)
    > +{
    > + struct device *dev = &spi->dev;
    > + struct mipi_dsi_device_info info = { };
    > + struct mipi_dsi_device *dsi;
    > + struct dbi_spi *dbi;
    > + int ret;
    > +
    > + dbi = devm_kzalloc(dev, sizeof(*dbi), GFP_KERNEL);
    > + if (!dbi)
    > + return -ENOMEM;
    > +
    > + dbi->host.dev = dev;
    > + dbi->host.ops = &dbi->host_ops;
    > + dbi->spi = spi;
    > + spi_set_drvdata(spi, dbi);
    > +
    > + dbi->dc = devm_gpiod_get_optional(dev, "dc", GPIOD_OUT_LOW);
    > + if (IS_ERR(dbi->dc)) {
    > + dev_err(dev, "Failed to get gpio 'dc'\n");
    > + return PTR_ERR(dbi->dc);
    > + }
    > +
    > + if (spi_is_bpw_supported(spi, 9))
    > + dbi->host.bus_types |= MIPI_DEVICE_TYPE_DBI_SPI_MODE1;
    > + if (dbi->dc)
    > + dbi->host.bus_types |= MIPI_DEVICE_TYPE_DBI_SPI_MODE3;
    > +
    > + if (!dbi->host.bus_types) {
    > + dev_err(dev, "Neither Type1 nor Type3 are supported\n");
    > + return -EINVAL;
    > + }
    > +
    > + dbi->host_ops.transfer = dbi_spi_transfer;
    > + dbi->host_ops.attach = dbi_spi_attach;
    > + dbi->host_ops.detach = dbi_spi_detach;
    > +
    > + mutex_init(&dbi->cmdlock);
    > +
    > + ret = mipi_dsi_host_register(&dbi->host);
    > + if (ret) {
    > + dev_err(dev, "Unable to register DSI host\n");
    > + return ret;
    > + }
    > +
    > + ret = devm_add_action_or_reset(dev, dbi_spi_host_unregister, &dbi->host);
    > + if (ret)
    > + return ret;
    > +
    > + /*
    > + * Register our own node as a MIPI DSI device.
    > + * This ensures that the panel driver will be probed.
    > + */
    > + info.channel = 0;
    > + info.node = of_node_get(dev->of_node);
    > +
    > + dsi = mipi_dsi_device_register_full(&dbi->host, &info);

    Two devices for the same OF node is asking for trouble :-S

    Looking at the other patches in this series, it seems that what you need
    from the DSI framework is DCS. I think we should then extract the DCS
    support to mipi_dcs_* functions, with two different backends, one for
    DSI and one for DBI. That way you will be able to support DBI panels
    with a single driver instead of splutting the support between two
    drivers (this one and the corresponding mipi_dsi_driver's).

    > + if (IS_ERR(dsi)) {
    > + dev_err(dev, "Failed to add DSI device\n");
    > + return PTR_ERR(dsi);
    > + }
    > +
    > + return 0;
    > +}
    > +
    > +static const struct of_device_id dbi_spi_of_match[] = {
    > + { .compatible = "adafruit,yx240qv29" },
    > + { .compatible = "leadtek,ltk035c5444t-spi" },
    > + { }
    > +};
    > +MODULE_DEVICE_TABLE(of, dbi_spi_of_match);
    > +
    > +static struct spi_driver dbi_spi_driver = {
    > + .driver = {
    > + .name = "dbi-spi",
    > + .of_match_table = dbi_spi_of_match,
    > + },
    > + .probe = dbi_spi_probe,
    > +};
    > +module_spi_driver(dbi_spi_driver);
    > +
    > +MODULE_DESCRIPTION("DBI SPI bus driver");
    > +MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
    > +MODULE_LICENSE("GPL");

    --
    Regards,

    Laurent Pinchart

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