drm/panel: s6e63m0: Break out SPI transport

This panel can be accessed using both SPI and DSI.

To make it possible to probe and use the device also from
a DSI bus, first break out the SPI support to its own file.

Since all the panel driver does is write DCS commands to
the panel, we pass a DCS write function to probe()
from each subdriver.

We make the Kconfig entry for SPI mode default so all
current users will continue to work.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Stephan Gerhold <stephan@gerhold.net>
Cc: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Acked-by: Paul Cercueil <paul@crapouillou.net>
Link: https://patchwork.freedesktop.org/patch/384873/

1 files changed, 89 insertions, 0 deletions

diff --git a/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c b/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c
new file mode 100644
index 000000000000..4082fbd75b79
--- /dev/null
+++ b/drivers/gpu/drm/panel/panel-samsung-s6e63m0-spi.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/spi/spi.h>
+#include <linux/delay.h>
+
+#include <drm/drm_print.h>
+
+#include "panel-samsung-s6e63m0.h"
+
+#define DATA_MASK	0x100
+
+static int s6e63m0_spi_write_word(struct device *dev, u16 data)
+{
+	struct spi_device *spi = to_spi_device(dev);
+	struct spi_transfer xfer = {
+		.len	= 2,
+		.tx_buf = &data,
+	};
+	struct spi_message msg;
+
+	spi_message_init(&msg);
+	spi_message_add_tail(&xfer, &msg);
+
+	return spi_sync(spi, &msg);
+}
+
+static int s6e63m0_spi_dcs_write(struct device *dev, const u8 *data, size_t len)
+{
+	int ret = 0;
+
+	DRM_DEV_DEBUG(dev, "SPI writing dcs seq: %*ph\n", (int)len, data);
+	ret = s6e63m0_spi_write_word(dev, *data);
+
+	while (!ret && --len) {
+		++data;
+		ret = s6e63m0_spi_write_word(dev, *data | DATA_MASK);
+	}
+
+	if (ret) {
+		DRM_DEV_ERROR(dev, "SPI error %d writing dcs seq: %*ph\n", ret,
+			      (int)len, data);
+	}
+
+	usleep_range(300, 310);
+
+	return ret;
+}
+
+static int s6e63m0_spi_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	int ret;
+
+	spi->bits_per_word = 9;
+	spi->mode = SPI_MODE_3;
+	ret = spi_setup(spi);
+	if (ret < 0) {
+		DRM_DEV_ERROR(dev, "spi setup failed.\n");
+		return ret;
+	}
+	return s6e63m0_probe(dev, s6e63m0_spi_dcs_write);
+}
+
+static int s6e63m0_spi_remove(struct spi_device *spi)
+{
+	return s6e63m0_remove(&spi->dev);
+}
+
+static const struct of_device_id s6e63m0_spi_of_match[] = {
+	{ .compatible = "samsung,s6e63m0" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, s6e63m0_spi_of_match);
+
+static struct spi_driver s6e63m0_spi_driver = {
+	.probe			= s6e63m0_spi_probe,
+	.remove			= s6e63m0_spi_remove,
+	.driver			= {
+		.name		= "panel-samsung-s6e63m0",
+		.of_match_table = s6e63m0_spi_of_match,
+	},
+};
+module_spi_driver(s6e63m0_spi_driver);
+
+MODULE_AUTHOR("Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>");
+MODULE_DESCRIPTION("s6e63m0 LCD SPI Driver");
+MODULE_LICENSE("GPL v2");