From 413f52f146f148827dd7a61ca599143f60ae3e3c Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Mon, 14 Jun 2021 20:11:34 +0200 Subject: [PATCH] drm/dbi: Support DBI typec1 read operations MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Implement SPI reads for typec1, for SPI controllers that can support 9bpw in addition to 8bpw (such as GPIO bit-banged SPI). 9bpw emulation is not supported but we have to start with something. This is used by s6e63m0 to read display MTP information which is used by the driver for backlight control. Reviewed-by: Noralf Trønnes Reviewed-by: Douglas Anderson Signed-off-by: Linus Walleij Link: https://patchwork.freedesktop.org/patch/msgid/20210614181135.1124445-1-linus.walleij@linaro.org --- drivers/gpu/drm/drm_mipi_dbi.c | 55 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 54 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c index 43a9b73..10b4e59 100644 --- a/drivers/gpu/drm/drm_mipi_dbi.c +++ b/drivers/gpu/drm/drm_mipi_dbi.c @@ -928,6 +928,59 @@ static int mipi_dbi_spi1_transfer(struct mipi_dbi *dbi, int dc, return 0; } +static int mipi_dbi_typec1_command_read(struct mipi_dbi *dbi, u8 *cmd, + u8 *data, size_t len) +{ + struct spi_device *spi = dbi->spi; + u32 speed_hz = min_t(u32, MIPI_DBI_MAX_SPI_READ_SPEED, + spi->max_speed_hz / 2); + struct spi_transfer tr[2] = { + { + .speed_hz = speed_hz, + .bits_per_word = 9, + .tx_buf = dbi->tx_buf9, + .len = 2, + }, { + .speed_hz = speed_hz, + .bits_per_word = 8, + .len = len, + .rx_buf = data, + }, + }; + struct spi_message m; + u16 *dst16; + int ret; + + if (!len) + return -EINVAL; + + if (!spi_is_bpw_supported(spi, 9)) { + /* + * FIXME: implement something like mipi_dbi_spi1e_transfer() but + * for reads using emulation. + */ + dev_err(&spi->dev, + "reading on host not supporting 9 bpw not yet implemented\n"); + return -EOPNOTSUPP; + } + + /* + * Turn the 8bit command into a 16bit version of the command in the + * buffer. Only 9 bits of this will be used when executing the actual + * transfer. + */ + dst16 = dbi->tx_buf9; + dst16[0] = *cmd; + + spi_message_init_with_transfers(&m, tr, ARRAY_SIZE(tr)); + ret = spi_sync(spi, &m); + + if (!ret) + MIPI_DBI_DEBUG_COMMAND(*cmd, data, len); + + return ret; +} + static int mipi_dbi_typec1_command(struct mipi_dbi *dbi, u8 *cmd, u8 *parameters, size_t num) { @@ -935,7 +988,7 @@ static int mipi_dbi_typec1_command(struct mipi_dbi *dbi, u8 *cmd, int ret; if (mipi_dbi_command_is_read(dbi, *cmd)) - return -EOPNOTSUPP; + return mipi_dbi_typec1_command_read(dbi, cmd, parameters, num); MIPI_DBI_DEBUG_COMMAND(*cmd, parameters, num); -- 2.7.4