[PATCH v4 2/3] drm/st7571-i2c: add support for Sitronix ST7571 LCD controller
Marcus Folkesson
marcus.folkesson at gmail.com
Tue Apr 15 05:58:59 UTC 2025
Sitronix ST7571 is a 4bit gray scale dot matrix LCD controller.
The controller has a SPI, I2C and 8bit parallel interface, this
driver is for the I2C interface only.
Reviewed-by: Thomas Zimmermann <tzimmrmann at suse.de>
Signed-off-by: Marcus Folkesson <marcus.folkesson at gmail.com>
---
drivers/gpu/drm/tiny/Kconfig | 11 +
drivers/gpu/drm/tiny/Makefile | 1 +
drivers/gpu/drm/tiny/st7571-i2c.c | 994 ++++++++++++++++++++++++++++++++++++++
3 files changed, 1006 insertions(+)
diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index 94cbdb1337c07f1628a33599a7130369b9d59d98..e4a55482e3bcd3f6851df1d322a14cbe1f96adfb 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -232,6 +232,17 @@ config TINYDRM_ST7586
If M is selected the module will be called st7586.
+config DRM_ST7571_I2C
+ tristate "DRM support for Sitronix ST7571 display panels (I2C)"
+ depends on DRM && I2C && MMU
+ select DRM_GEM_SHMEM_HELPER
+ select DRM_KMS_HELPER
+ select REGMAP_I2C
+ help
+ DRM driver for Sitronix ST7571 panels controlled over I2C.
+
+ if M is selected the module will be called st7571-i2c.
+
config TINYDRM_ST7735R
tristate "DRM support for Sitronix ST7715R/ST7735R display panels"
depends on DRM && SPI
diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
index 60816d2eb4ff93b87228ed8eadd60a0a33a1144b..eab7568c92c880cfdf7c2f0b9c4bfac4685dbe95 100644
--- a/drivers/gpu/drm/tiny/Makefile
+++ b/drivers/gpu/drm/tiny/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_DRM_GM12U320) += gm12u320.o
obj-$(CONFIG_DRM_OFDRM) += ofdrm.o
obj-$(CONFIG_DRM_PANEL_MIPI_DBI) += panel-mipi-dbi.o
obj-$(CONFIG_DRM_SIMPLEDRM) += simpledrm.o
+obj-$(CONFIG_DRM_ST7571_I2C) += st7571-i2c.o
obj-$(CONFIG_TINYDRM_HX8357D) += hx8357d.o
obj-$(CONFIG_TINYDRM_ILI9163) += ili9163.o
obj-$(CONFIG_TINYDRM_ILI9225) += ili9225.o
diff --git a/drivers/gpu/drm/tiny/st7571-i2c.c b/drivers/gpu/drm/tiny/st7571-i2c.c
new file mode 100644
index 0000000000000000000000000000000000000000..97a8285a6fa60759bdb7018cc46663634afc88ae
--- /dev/null
+++ b/drivers/gpu/drm/tiny/st7571-i2c.c
@@ -0,0 +1,994 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for Sitronix ST7571, a 4 level gray scale dot matrix LCD controller
+ *
+ * Copyright (C) 2025 Marcus Folkesson <marcus.folkesson at gmail.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include <drm/clients/drm_client_setup.h>
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_encoder.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fbdev_shmem.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_atomic_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_module.h>
+#include <drm/drm_plane.h>
+#include <drm/drm_probe_helper.h>
+
+#include <video/display_timing.h>
+#include <video/of_display_timing.h>
+
+#define ST7571_COMMAND_MODE (0x00)
+#define ST7571_DATA_MODE (0x40)
+
+/* Normal mode command set */
+#define ST7571_DISPLAY_OFF (0xae)
+#define ST7571_DISPLAY_ON (0xaf)
+#define ST7571_OSC_ON (0xab)
+#define ST7571_SET_COLUMN_LSB(c) (0x00 | ((c) & 0xf))
+#define ST7571_SET_COLUMN_MSB(c) (0x10 | ((c) >> 4))
+#define ST7571_SET_COM0_LSB(x) ((x) & 0x7f)
+#define ST7571_SET_COM0_MSB (0x44)
+#define ST7571_SET_COM_SCAN_DIR(d) (0xc0 | (((d) << 3) & 0x8))
+#define ST7571_SET_CONTRAST_LSB(c) ((c) & 0x3f)
+#define ST7571_SET_CONTRAST_MSB (0x81)
+#define ST7571_SET_DISPLAY_DUTY_LSB(d) ((d) & 0xff)
+#define ST7571_SET_DISPLAY_DUTY_MSB (0x48)
+#define ST7571_SET_ENTIRE_DISPLAY_ON(p) (0xa4 | ((p) & 0x1))
+#define ST7571_SET_LCD_BIAS(b) (0x50 | ((b) & 0x7))
+#define ST7571_SET_MODE_LSB(m) ((m) & 0xfc)
+#define ST7571_SET_MODE_MSB (0x38)
+#define ST7571_SET_PAGE(p) (0xb0 | (p))
+#define ST7571_SET_POWER(p) (0x28 | ((p) & 0x7))
+#define ST7571_SET_REGULATOR_REG(r) (0x20 | ((r) & 0x7))
+#define ST7571_SET_REVERSE(r) (0xa6 | ((r) & 0x1))
+#define ST7571_SET_SEG_SCAN_DIR(d) (0xa0 | ((d) & 0x1))
+#define ST7571_SET_START_LINE_LSB(l) ((l) & 0x3f)
+#define ST7571_SET_START_LINE_MSB (0x40)
+
+/* Extension command set 3 */
+#define ST7571_COMMAND_SET_3 (0x7b)
+#define ST7571_SET_COLOR_MODE(c) (0x10 | ((c) & 0x1))
+#define ST7571_COMMAND_SET_NORMAL (0x00)
+
+#define ST7571_PAGE_HEIGHT 8
+
+#define DRIVER_NAME "st7571"
+#define DRIVER_DESC "ST7571 DRM driver"
+#define DRIVER_MAJOR 1
+#define DRIVER_MINOR 0
+
+enum st7571_color_mode {
+ ST7571_COLOR_MODE_GRAY = 0,
+ ST7571_COLOR_MODE_BLACKWHITE = 1,
+};
+
+struct st7571_device;
+
+struct st7571_panel_constraints {
+ u32 min_nlines;
+ u32 max_nlines;
+ u32 min_ncols;
+ u32 max_ncols;
+ bool support_grayscale;
+};
+
+struct st7571_panel_data {
+ int (*init)(struct st7571_device *st7571);
+ struct st7571_panel_constraints constraints;
+};
+
+struct st7571_panel_format {
+ void (*prepare_buffer)(struct st7571_device *st7571,
+ const struct iosys_map *vmap,
+ struct drm_framebuffer *fb,
+ struct drm_rect *rect,
+ struct drm_format_conv_state *fmtcnv_state);
+ int (*update_rect)(struct drm_framebuffer *fb, struct drm_rect *rect);
+ enum st7571_color_mode mode;
+ const u8 nformats;
+ const u32 formats[];
+};
+
+struct st7571_device {
+ struct drm_device dev;
+
+ struct drm_plane primary_plane;
+ struct drm_crtc crtc;
+ struct drm_encoder encoder;
+ struct drm_connector connector;
+
+ struct drm_display_mode mode;
+
+ const struct st7571_panel_format *pformat;
+ const struct st7571_panel_data *pdata;
+ struct i2c_client *client;
+ struct gpio_desc *reset;
+ struct regmap *regmap;
+
+ /*
+ * Depending on the hardware design, the acknowledge signal may be hard to
+ * recognize as a valid logic "0" level.
+ * Therefor, ignore NAK if possible to stay compatible with most hardware designs
+ * and off-the-shelf panels out there.
+ *
+ * From section 6.4 MICROPOCESSOR INTERFACE section in the datasheet:
+ *
+ * "By connecting SDA_OUT to SDA_IN externally, the SDA line becomes fully
+ * I2C interface compatible.
+ * Separating acknowledge-output from serial data
+ * input is advantageous for chip-on-glass (COG) applications. In COG
+ * applications, the ITO resistance and the pull-up resistor will form a
+ * voltage divider, which affects acknowledge-signal level. Larger ITO
+ * resistance will raise the acknowledged-signal level and system cannot
+ * recognize this level as a valid logic “0” level. By separating SDA_IN from
+ * SDA_OUT, the IC can be used in a mode that ignores the acknowledge-bit.
+ * For applications which check acknowledge-bit, it is necessary to minimize
+ * the ITO resistance of the SDA_OUT trace to guarantee a valid low level."
+ *
+ */
+ bool ignore_nak;
+
+
+ bool grayscale;
+ u32 height_mm;
+ u32 width_mm;
+ u32 startline;
+ u32 nlines;
+ u32 ncols;
+ u32 bpp;
+
+ /* Intermediate buffer in LCD friendly format */
+ u8 *hwbuf;
+
+ /* Row of (transformed) pixels ready to be written to the display */
+ u8 *row;
+};
+
+static inline struct st7571_device *drm_to_st7571(struct drm_device *dev)
+{
+ return container_of(dev, struct st7571_device, dev);
+}
+
+static int st7571_regmap_write(void *context, const void *data, size_t count)
+{
+ struct i2c_client *client = context;
+ struct st7571_device *st7571 = i2c_get_clientdata(client);
+ int ret;
+
+ struct i2c_msg msg = {
+ .addr = st7571->client->addr,
+ .flags = st7571->ignore_nak ? I2C_M_IGNORE_NAK : 0,
+ .len = count,
+ .buf = (u8 *)data
+ };
+
+ ret = i2c_transfer(st7571->client->adapter, &msg, 1);
+
+ /*
+ * Unfortunately, there is no way to check if the transfer failed because of
+ * a NAK or something else as I2C bus drivers use different return values for NAK.
+ *
+ * However, if the transfer fails and ignore_nak is set, we know it is an error.
+ */
+ if (ret < 0 && st7571->ignore_nak)
+ return ret;
+
+ return 0;
+}
+
+static int st7571_regmap_read(void *context, const void *reg_buf,
+ size_t reg_size, void *val_buf, size_t val_size)
+{
+ return -EOPNOTSUPP;
+}
+
+static int st7571_send_command_list(struct st7571_device *st7571,
+ const u8 *cmd_list, size_t len)
+{
+ int ret;
+
+ for (int i = 0; i < len; i++) {
+ ret = regmap_write(st7571->regmap, ST7571_COMMAND_MODE, cmd_list[i]);
+ if (ret < 0)
+ return ret;
+ }
+
+ return ret;
+}
+
+static inline u8 st7571_transform_xy(const char *p, int x, int y)
+{
+ int xrest = x % 8;
+ u8 result = 0;
+
+ /*
+ * Transforms an (x, y) pixel coordinate into a vertical 8-bit
+ * column from the framebuffer. It calculates the corresponding byte in the
+ * framebuffer, extracts the bit at the given x position across 8 consecutive
+ * rows, and packs those bits into a single byte.
+ *
+ * Return an 8-bit value representing a vertical column of pixels.
+ */
+ x = x / 8;
+ y = (y / 8) * 8;
+
+ for (int i = 0; i < 8; i++) {
+ int row_idx = y + i;
+ u8 byte = p[row_idx * 16 + x];
+ u8 bit = (byte >> xrest) & 1;
+
+ result |= (bit << i);
+ }
+
+ return result;
+}
+
+static int st7571_set_position(struct st7571_device *st7571, int x, int y)
+{
+ u8 cmd_list[] = {
+ ST7571_SET_COLUMN_LSB(x),
+ ST7571_SET_COLUMN_MSB(x),
+ ST7571_SET_PAGE(y / ST7571_PAGE_HEIGHT),
+ };
+
+ return st7571_send_command_list(st7571, cmd_list, ARRAY_SIZE(cmd_list));
+}
+
+static int st7571_fb_clear_screen(struct st7571_device *st7571)
+{
+ u32 npixels = st7571->ncols * round_up(st7571->nlines, ST7571_PAGE_HEIGHT) * st7571->bpp;
+ char pixelvalue = 0x00;
+
+ for (int i = 0; i < npixels; i++)
+ regmap_bulk_write(st7571->regmap, ST7571_DATA_MODE, &pixelvalue, 1);
+
+ return 0;
+}
+
+static void st7571_prepare_buffer_monochrome(struct st7571_device *st7571,
+ const struct iosys_map *vmap,
+ struct drm_framebuffer *fb,
+ struct drm_rect *rect,
+ struct drm_format_conv_state *fmtcnv_state)
+{
+ unsigned int dst_pitch;
+ struct iosys_map dst;
+ u32 size;
+
+ switch (fb->format->format) {
+ case DRM_FORMAT_XRGB8888:
+ dst_pitch = DIV_ROUND_UP(drm_rect_width(rect), 8);
+ iosys_map_set_vaddr(&dst, st7571->hwbuf);
+
+ drm_fb_xrgb8888_to_mono(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
+ break;
+
+ case DRM_FORMAT_R1:
+ size = (rect->x2 - rect->x1) * (rect->y2 - rect->y1) / 8;
+ memcpy(st7571->hwbuf, vmap->vaddr, size);
+ break;
+ }
+}
+
+static void st7571_prepare_buffer_grayscale(struct st7571_device *st7571,
+ const struct iosys_map *vmap,
+ struct drm_framebuffer *fb,
+ struct drm_rect *rect,
+ struct drm_format_conv_state *fmtcnv_state)
+{
+ u32 size = (rect->x2 - rect->x1) * (rect->y2 - rect->y1) / 8;
+ unsigned int dst_pitch;
+ struct iosys_map dst;
+
+ switch (fb->format->format) {
+ case DRM_FORMAT_XRGB8888: /* Only support XRGB8888 in monochrome mode */
+ dst_pitch = DIV_ROUND_UP(drm_rect_width(rect), 8);
+ iosys_map_set_vaddr(&dst, st7571->hwbuf);
+
+ drm_fb_xrgb8888_to_mono(&dst, &dst_pitch, vmap, fb, rect, fmtcnv_state);
+ break;
+
+ case DRM_FORMAT_R1:
+ size = (rect->x2 - rect->x1) * (rect->y2 - rect->y1) / 8;
+ memcpy(st7571->hwbuf, vmap->vaddr, size);
+ break;
+
+ case DRM_FORMAT_R2:
+ size = (rect->x2 - rect->x1) * (rect->y2 - rect->y1) / 4;
+ memcpy(st7571->hwbuf, vmap->vaddr, size);
+ break;
+ };
+
+}
+
+static int st7571_fb_update_rect_monochrome(struct drm_framebuffer *fb, struct drm_rect *rect)
+{
+ struct st7571_device *st7571 = drm_to_st7571(fb->dev);
+ char *row = st7571->row;
+
+ /* Align y to display page boundaries */
+ rect->y1 = round_down(rect->y1, ST7571_PAGE_HEIGHT);
+ rect->y2 = min_t(unsigned int, round_up(rect->y2, ST7571_PAGE_HEIGHT), st7571->nlines);
+
+ for (int y = rect->y1; y < rect->y2; y += ST7571_PAGE_HEIGHT) {
+ for (int x = rect->x1; x < rect->x2; x++)
+ row[x] = st7571_transform_xy(st7571->hwbuf, x, y);
+
+ st7571_set_position(st7571, rect->x1, y);
+
+ /* TODO: Investige why we can't write multiple bytes at once */
+ for (int x = rect->x1; x < rect->x2; x++)
+ regmap_bulk_write(st7571->regmap, ST7571_DATA_MODE, row + x, 1);
+ }
+
+ return 0;
+}
+
+static int st7571_fb_update_rect_grayscale(struct drm_framebuffer *fb, struct drm_rect *rect)
+{
+ struct st7571_device *st7571 = drm_to_st7571(fb->dev);
+ uint32_t format = fb->format->format;
+ char *row = st7571->row;
+ int x1;
+ int x2;
+
+ /* Align y to display page boundaries */
+ rect->y1 = round_down(rect->y1, ST7571_PAGE_HEIGHT);
+ rect->y2 = min_t(unsigned int, round_up(rect->y2, ST7571_PAGE_HEIGHT), st7571->nlines);
+
+ switch (format) {
+ case DRM_FORMAT_XRGB8888:
+ /* Threated as monochrome (R1) */
+ fallthrough;
+ case DRM_FORMAT_R1:
+ x1 = rect->x1;
+ x2 = rect->x2;
+ break;
+ case DRM_FORMAT_R2:
+ x1 = rect->x1 * 2;
+ x2 = rect->x2 * 2;
+ break;
+ }
+
+ for (int y = rect->y1; y < rect->y2; y += ST7571_PAGE_HEIGHT) {
+ for (int x = x1; x < x2; x++)
+ row[x] = st7571_transform_xy(st7571->hwbuf, x, y);
+
+ st7571_set_position(st7571, rect->x1, y);
+
+ /* TODO: Investige why we can't write multiple bytes at once */
+ for (int x = x1; x < x2; x++) {
+ regmap_bulk_write(st7571->regmap, ST7571_DATA_MODE, row + x, 1);
+
+ /* Write monochrome formats twice */
+ if (format == DRM_FORMAT_R1 || format == DRM_FORMAT_XRGB8888)
+ regmap_bulk_write(st7571->regmap, ST7571_DATA_MODE, row + x, 1);
+ }
+ }
+
+ return 0;
+}
+
+static int st7571_connector_get_modes(struct drm_connector *conn)
+{
+ struct st7571_device *st7571 = drm_to_st7571(conn->dev);
+
+ return drm_connector_helper_get_modes_fixed(conn, &st7571->mode);
+}
+
+static const struct drm_connector_helper_funcs st7571_connector_helper_funcs = {
+ .get_modes = st7571_connector_get_modes,
+};
+
+static const struct st7571_panel_format st7571_monochrome = {
+ .prepare_buffer = st7571_prepare_buffer_monochrome,
+ .update_rect = st7571_fb_update_rect_monochrome,
+ .mode = ST7571_COLOR_MODE_BLACKWHITE,
+ .formats = {
+ DRM_FORMAT_XRGB8888,
+ DRM_FORMAT_R1,
+ },
+ .nformats = 2,
+};
+
+static const struct st7571_panel_format st7571_grayscale = {
+ .prepare_buffer = st7571_prepare_buffer_grayscale,
+ .update_rect = st7571_fb_update_rect_grayscale,
+ .mode = ST7571_COLOR_MODE_GRAY,
+ .formats = {
+ DRM_FORMAT_XRGB8888,
+ DRM_FORMAT_R1,
+ DRM_FORMAT_R2,
+ },
+ .nformats = 3,
+};
+
+static const uint64_t st7571_primary_plane_fmtmods[] = {
+ DRM_FORMAT_MOD_LINEAR,
+ DRM_FORMAT_MOD_INVALID
+};
+
+static int st7571_primary_plane_helper_atomic_check(struct drm_plane *plane,
+ struct drm_atomic_state *state)
+{
+ struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, plane);
+ struct drm_crtc *new_crtc = new_plane_state->crtc;
+ struct drm_crtc_state *new_crtc_state = NULL;
+
+ if (new_crtc)
+ new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
+
+ return drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
+ DRM_PLANE_NO_SCALING,
+ DRM_PLANE_NO_SCALING,
+ false, false);
+}
+
+static void st7571_primary_plane_helper_atomic_update(struct drm_plane *plane,
+ struct drm_atomic_state *state)
+{
+ struct drm_plane_state *old_plane_state = drm_atomic_get_old_plane_state(state, plane);
+ struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
+ struct drm_shadow_plane_state *shadow_plane_state = to_drm_shadow_plane_state(plane_state);
+ struct drm_framebuffer *fb = plane_state->fb;
+ struct drm_atomic_helper_damage_iter iter;
+ struct drm_device *dev = plane->dev;
+ struct drm_rect damage;
+ struct st7571_device *st7571 = drm_to_st7571(plane->dev);
+ int ret, idx;
+
+ if (!fb)
+ return; /* no framebuffer; plane is disabled */
+
+ ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
+ if (ret)
+ return;
+
+ if (!drm_dev_enter(dev, &idx))
+ goto out_drm_gem_fb_end_cpu_access;
+
+ drm_atomic_helper_damage_iter_init(&iter, old_plane_state, plane_state);
+ drm_atomic_for_each_plane_damage(&iter, &damage) {
+
+ st7571->pformat->prepare_buffer(st7571,
+ &shadow_plane_state->data[0],
+ fb, &damage,
+ &shadow_plane_state->fmtcnv_state);
+
+ st7571->pformat->update_rect(fb, &damage);
+ }
+
+ drm_dev_exit(idx);
+
+out_drm_gem_fb_end_cpu_access:
+ drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
+}
+
+static void st7571_primary_plane_helper_atomic_disable(struct drm_plane *plane,
+ struct drm_atomic_state *state)
+{
+ struct drm_device *dev = plane->dev;
+ struct st7571_device *st7571 = drm_to_st7571(plane->dev);
+ int idx;
+
+ if (!drm_dev_enter(dev, &idx))
+ return;
+
+ st7571_fb_clear_screen(st7571);
+ drm_dev_exit(idx);
+}
+
+static const struct drm_plane_helper_funcs st7571_primary_plane_helper_funcs = {
+ DRM_GEM_SHADOW_PLANE_HELPER_FUNCS,
+ .atomic_check = st7571_primary_plane_helper_atomic_check,
+ .atomic_update = st7571_primary_plane_helper_atomic_update,
+ .atomic_disable = st7571_primary_plane_helper_atomic_disable,
+};
+
+static const struct drm_plane_funcs st7571_primary_plane_funcs = {
+ .update_plane = drm_atomic_helper_update_plane,
+ .disable_plane = drm_atomic_helper_disable_plane,
+ .destroy = drm_plane_cleanup,
+ DRM_GEM_SHADOW_PLANE_FUNCS,
+};
+
+/*
+ * CRTC
+ */
+
+static enum drm_mode_status st7571_crtc_mode_valid(struct drm_crtc *crtc,
+ const struct drm_display_mode *mode)
+{
+ struct st7571_device *st7571 = drm_to_st7571(crtc->dev);
+
+ return drm_crtc_helper_mode_valid_fixed(crtc, mode, &st7571->mode);
+}
+
+static const struct drm_crtc_helper_funcs st7571_crtc_helper_funcs = {
+ .atomic_check = drm_crtc_helper_atomic_check,
+ .mode_valid = st7571_crtc_mode_valid,
+};
+
+static const struct drm_crtc_funcs st7571_crtc_funcs = {
+ .reset = drm_atomic_helper_crtc_reset,
+ .destroy = drm_crtc_cleanup,
+ .set_config = drm_atomic_helper_set_config,
+ .page_flip = drm_atomic_helper_page_flip,
+ .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
+ .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+};
+
+/*
+ * Encoder
+ */
+
+static void ssd130x_encoder_atomic_enable(struct drm_encoder *encoder,
+ struct drm_atomic_state *state)
+{
+ struct drm_device *drm = encoder->dev;
+ struct st7571_device *st7571 = drm_to_st7571(drm);
+ u8 command = ST7571_DISPLAY_ON;
+ int ret;
+
+ ret = st7571->pdata->init(st7571);
+ if (ret)
+ return;
+
+ st7571_send_command_list(st7571, &command, 1);
+}
+
+static void ssd130x_encoder_atomic_disable(struct drm_encoder *encoder,
+ struct drm_atomic_state *state)
+{
+ struct drm_device *drm = encoder->dev;
+ struct st7571_device *st7571 = drm_to_st7571(drm);
+ u8 command = ST7571_DISPLAY_OFF;
+
+ st7571_send_command_list(st7571, &command, 1);
+}
+
+
+static const struct drm_encoder_funcs st7571_encoder_funcs = {
+ .destroy = drm_encoder_cleanup,
+
+};
+
+static const struct drm_encoder_helper_funcs st7571_encoder_helper_funcs = {
+ .atomic_enable = ssd130x_encoder_atomic_enable,
+ .atomic_disable = ssd130x_encoder_atomic_disable,
+};
+
+/*
+ * Connector
+ */
+
+static const struct drm_connector_funcs st7571_connector_funcs = {
+ .reset = drm_atomic_helper_connector_reset,
+ .fill_modes = drm_helper_probe_single_connector_modes,
+ .destroy = drm_connector_cleanup,
+ .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+ .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static const struct drm_mode_config_funcs st7571_mode_config_funcs = {
+ .fb_create = drm_gem_fb_create_with_dirty,
+ .atomic_check = drm_atomic_helper_check,
+ .atomic_commit = drm_atomic_helper_commit,
+};
+
+static struct drm_display_mode st7571_mode(struct st7571_device *st7571)
+{
+ struct drm_display_mode mode = {
+ DRM_SIMPLE_MODE(st7571->ncols, st7571->nlines,
+ st7571->width_mm, st7571->height_mm),
+ };
+
+ return mode;
+}
+
+static int st7571_mode_config_init(struct st7571_device *st7571)
+{
+ struct drm_device *dev = &st7571->dev;
+ const struct st7571_panel_constraints *constraints = &st7571->pdata->constraints;
+ int ret;
+
+ ret = drmm_mode_config_init(dev);
+ if (ret)
+ return ret;
+
+ dev->mode_config.min_width = constraints->min_ncols;
+ dev->mode_config.min_height = constraints->min_nlines;
+ dev->mode_config.max_width = constraints->max_ncols;
+ dev->mode_config.max_height = constraints->max_nlines;
+ dev->mode_config.preferred_depth = 24;
+ dev->mode_config.funcs = &st7571_mode_config_funcs;
+
+ return 0;
+}
+
+static int st7571_plane_init(struct st7571_device *st7571,
+ const struct st7571_panel_format *pformat)
+{
+ struct drm_plane *primary_plane = &st7571->primary_plane;
+ struct drm_device *dev = &st7571->dev;
+ int ret;
+
+ ret = drm_universal_plane_init(dev, primary_plane, 0,
+ &st7571_primary_plane_funcs,
+ pformat->formats,
+ pformat->nformats,
+ st7571_primary_plane_fmtmods,
+ DRM_PLANE_TYPE_PRIMARY, NULL);
+ if (ret)
+ return ret;
+
+ drm_plane_helper_add(primary_plane, &st7571_primary_plane_helper_funcs);
+ drm_plane_enable_fb_damage_clips(primary_plane);
+
+ return 0;
+}
+
+static int st7571_crtc_init(struct st7571_device *st7571)
+{
+ struct drm_plane *primary_plane = &st7571->primary_plane;
+ struct drm_crtc *crtc = &st7571->crtc;
+ struct drm_device *dev = &st7571->dev;
+ int ret;
+
+ ret = drm_crtc_init_with_planes(dev, crtc, primary_plane, NULL,
+ &st7571_crtc_funcs, NULL);
+ if (ret)
+ return ret;
+
+ drm_crtc_helper_add(crtc, &st7571_crtc_helper_funcs);
+
+ return 0;
+}
+
+static int st7571_encoder_init(struct st7571_device *st7571)
+{
+ struct drm_encoder *encoder = &st7571->encoder;
+ struct drm_crtc *crtc = &st7571->crtc;
+ struct drm_device *dev = &st7571->dev;
+ int ret;
+
+ ret = drm_encoder_init(dev, encoder, &st7571_encoder_funcs, DRM_MODE_ENCODER_NONE, NULL);
+ if (ret)
+ return ret;
+
+ drm_encoder_helper_add(encoder, &st7571_encoder_helper_funcs);
+
+ encoder->possible_crtcs = drm_crtc_mask(crtc);
+
+ return 0;
+}
+
+static int st7571_connector_init(struct st7571_device *st7571)
+{
+ struct drm_connector *connector = &st7571->connector;
+ struct drm_encoder *encoder = &st7571->encoder;
+ struct drm_device *dev = &st7571->dev;
+ int ret;
+
+ ret = drm_connector_init(dev, connector, &st7571_connector_funcs,
+ DRM_MODE_CONNECTOR_Unknown);
+ if (ret)
+ return ret;
+
+ drm_connector_helper_add(connector, &st7571_connector_helper_funcs);
+
+ return drm_connector_attach_encoder(connector, encoder);
+}
+
+DEFINE_DRM_GEM_FOPS(st7571_fops);
+
+static const struct drm_driver st7571_driver = {
+ .driver_features = DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
+
+ .name = DRIVER_NAME,
+ .desc = DRIVER_DESC,
+ .major = DRIVER_MAJOR,
+ .minor = DRIVER_MINOR,
+
+ .fops = &st7571_fops,
+ DRM_GEM_SHMEM_DRIVER_OPS,
+ DRM_FBDEV_SHMEM_DRIVER_OPS,
+};
+
+static const struct regmap_bus st7571_regmap_bus = {
+ .read = st7571_regmap_read,
+ .write = st7571_regmap_write,
+};
+
+static const struct regmap_config st7571_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
+ .use_single_write = true,
+};
+
+static int st7571_validate_parameters(struct st7571_device *st7571)
+{
+ struct device *dev = st7571->dev.dev;
+ const struct st7571_panel_constraints *constraints = &st7571->pdata->constraints;
+
+ if (st7571->width_mm == 0) {
+ dev_err(dev, "Invalid panel width\n");
+ return -EINVAL;
+ }
+
+ if (st7571->height_mm == 0) {
+ dev_err(dev, "Invalid panel height\n");
+ return -EINVAL;
+ }
+
+ if (st7571->nlines < constraints->min_nlines ||
+ st7571->nlines > constraints->max_nlines) {
+ dev_err(dev, "Invalid timing configuration.\n");
+ return -EINVAL;
+ }
+
+ if (st7571->startline + st7571->nlines > constraints->max_nlines) {
+ dev_err(dev, "Invalid timing configuration.\n");
+ return -EINVAL;
+ }
+
+ if (st7571->ncols < constraints->min_ncols ||
+ st7571->ncols > constraints->max_ncols) {
+ dev_err(dev, "Invalid timing configuration.\n");
+ return -EINVAL;
+ }
+
+ if (st7571->grayscale && !constraints->support_grayscale) {
+ dev_err(dev, "Grayscale not supported\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int st7571_parse_dt(struct st7571_device *st7571)
+{
+ struct device *dev = &st7571->client->dev;
+ struct device_node *np = dev->of_node;
+ struct display_timing dt;
+ int ret;
+
+ ret = of_get_display_timing(np, "panel-timing", &dt);
+ if (ret) {
+ dev_err(dev, "Failed to get display timing from DT\n");
+ return ret;
+ }
+
+ of_property_read_u32(np, "width-mm", &st7571->width_mm);
+ of_property_read_u32(np, "height-mm", &st7571->height_mm);
+ st7571->grayscale = of_property_read_bool(np, "sitronix,grayscale");
+
+ if (st7571->grayscale) {
+ st7571->pformat = &st7571_grayscale;
+ st7571->bpp = 2;
+ } else {
+ st7571->pformat = &st7571_monochrome;
+ st7571->bpp = 1;
+ }
+
+ st7571->startline = dt.vfront_porch.typ;
+ st7571->nlines = dt.vactive.typ;
+ st7571->ncols = dt.hactive.typ;
+
+ st7571->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(st7571->reset))
+ return PTR_ERR(st7571->reset);
+
+ return 0;
+}
+
+static void st7571_reset(struct st7571_device *st7571)
+{
+ gpiod_set_value_cansleep(st7571->reset, 1);
+ udelay(20);
+ gpiod_set_value_cansleep(st7571->reset, 0);
+}
+
+static int st7571_lcd_init(struct st7571_device *st7571)
+{
+ /*
+ * Most of the initialization sequence is taken directly from the
+ * referential initial code in the ST7571 datasheet.
+ */
+ u8 commands[] = {
+ ST7571_DISPLAY_OFF,
+ ST7571_SET_MODE_MSB,
+
+ ST7571_SET_MODE_LSB(0x94),
+ ST7571_SET_SEG_SCAN_DIR(0),
+ ST7571_SET_COM_SCAN_DIR(1),
+
+ ST7571_SET_COM0_MSB,
+ ST7571_SET_COM0_LSB(0x00),
+
+ ST7571_SET_START_LINE_MSB,
+ ST7571_SET_START_LINE_LSB(st7571->startline),
+
+ ST7571_OSC_ON,
+ ST7571_SET_REGULATOR_REG(5),
+ ST7571_SET_CONTRAST_MSB,
+ ST7571_SET_CONTRAST_LSB(0x33),
+ ST7571_SET_LCD_BIAS(0x04),
+ ST7571_SET_DISPLAY_DUTY_MSB,
+ ST7571_SET_DISPLAY_DUTY_LSB(st7571->nlines),
+
+ ST7571_COMMAND_SET_3,
+ ST7571_SET_COLOR_MODE(st7571->pformat->mode),
+ ST7571_COMMAND_SET_NORMAL,
+
+ ST7571_SET_POWER(0x4), /* Power Control, VC: ON, VR: OFF, VF: OFF */
+ ST7571_SET_POWER(0x6), /* Power Control, VC: ON, VR: ON, VF: OFF */
+ ST7571_SET_POWER(0x7), /* Power Control, VC: ON, VR: ON, VF: ON */
+
+ ST7571_SET_REVERSE(0),
+ ST7571_SET_ENTIRE_DISPLAY_ON(0),
+ };
+
+ /* Perform a reset before initializing the controller */
+ st7571_reset(st7571);
+
+ return st7571_send_command_list(st7571, commands, ARRAY_SIZE(commands));
+}
+
+
+static int st7571_probe(struct i2c_client *client)
+{
+ struct st7571_device *st7571;
+ struct drm_device *dev;
+ int ret;
+
+ st7571 = devm_drm_dev_alloc(&client->dev, &st7571_driver,
+ struct st7571_device, dev);
+ if (IS_ERR(st7571))
+ return PTR_ERR(st7571);
+
+ dev = &st7571->dev;
+ st7571->client = client;
+ i2c_set_clientdata(client, st7571);
+ st7571->pdata = device_get_match_data(&client->dev);
+
+ ret = st7571_parse_dt(st7571);
+ if (ret)
+ return ret;
+
+ ret = st7571_validate_parameters(st7571);
+ if (ret)
+ return ret;
+
+
+ st7571->mode = st7571_mode(st7571);
+
+ /*
+ * The hardware design could make it hard to detect a NAK on the I2C bus.
+ * If the adapter does not support protocol mangling do
+ * not set the I2C_M_IGNORE_NAK flag at the expense * of possible
+ * cruft in the logs.
+ */
+ if (i2c_check_functionality(client->adapter, I2C_FUNC_PROTOCOL_MANGLING))
+ st7571->ignore_nak = true;
+
+ st7571->regmap = devm_regmap_init(&client->dev, &st7571_regmap_bus,
+ client, &st7571_regmap_config);
+ if (IS_ERR(st7571->regmap)) {
+ return dev_err_probe(&client->dev, PTR_ERR(st7571->regmap),
+ "Failed to initialize regmap\n");
+ }
+
+ st7571->hwbuf = devm_kzalloc(&client->dev,
+ (st7571->nlines * st7571->ncols * st7571->bpp) / 8,
+ GFP_KERNEL);
+ if (IS_ERR(st7571->hwbuf))
+ return dev_err_probe(&client->dev, PTR_ERR(st7571->hwbuf),
+ "Failed to allocate intermediate buffer\n");
+
+ st7571->row = devm_kzalloc(&client->dev,
+ (st7571->ncols * st7571->bpp),
+ GFP_KERNEL);
+ if (IS_ERR(st7571->row))
+ return dev_err_probe(&client->dev, PTR_ERR(st7571->row),
+ "Failed to allocate row buffer\n");
+
+ ret = st7571_mode_config_init(st7571);
+ if (ret)
+ return dev_err_probe(&client->dev, ret,
+ "Failed to initialize mode config\n");
+
+ ret = st7571_plane_init(st7571, st7571->pformat);
+ if (ret)
+ return dev_err_probe(&client->dev, ret,
+ "Failed to initialize primary plane\n");
+
+ ret = st7571_crtc_init(st7571);
+ if (ret < 0)
+ return dev_err_probe(&client->dev, ret,
+ "Failed to initialize CRTC\n");
+
+ ret = st7571_encoder_init(st7571);
+ if (ret < 0)
+ return dev_err_probe(&client->dev, ret,
+ "Failed to initialize encoder\n");
+
+ ret = st7571_connector_init(st7571);
+ if (ret < 0)
+ return dev_err_probe(&client->dev, ret,
+ "Failed to initialize connector\n");
+
+ drm_mode_config_reset(dev);
+
+ ret = drm_dev_register(dev, 0);
+ if (ret)
+ return dev_err_probe(&client->dev, ret,
+ "Failed to register DRM device\n");
+
+ drm_client_setup(dev, NULL);
+ return 0;
+}
+
+static void st7571_remove(struct i2c_client *client)
+{
+ struct st7571_device *st7571 = i2c_get_clientdata(client);
+
+ drm_dev_unplug(&st7571->dev);
+}
+
+struct st7571_panel_data st7571_config = {
+ .init = st7571_lcd_init,
+ .constraints = {
+ .min_nlines = 1,
+ .max_nlines = 128,
+ .min_ncols = 128,
+ .max_ncols = 128,
+ .support_grayscale = true,
+ },
+};
+
+static const struct of_device_id st7571_of_match[] = {
+ { .compatible = "sitronix,st7571", .data = &st7571_config },
+ {},
+};
+MODULE_DEVICE_TABLE(of, st7571_of_match);
+
+
+static const struct i2c_device_id st7571_id[] = {
+ { "st7571", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, st7571_id);
+
+static struct i2c_driver st7571_i2c_driver = {
+ .driver = {
+ .name = "st7571",
+ .of_match_table = st7571_of_match,
+ },
+ .probe = st7571_probe,
+ .remove = st7571_remove,
+ .id_table = st7571_id,
+};
+
+module_i2c_driver(st7571_i2c_driver);
+
+MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson at gmail.com>");
+MODULE_DESCRIPTION("DRM Driver for Sitronix ST7571 LCD controller");
+MODULE_LICENSE("GPL");
--
2.49.0
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