drm/tinydrm: Rename folder to tiny

The drm in tinydrm is superfluous so rename to tiny.

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190725105132.22545-3-noralf@tronnes.org

1 files changed, 1212 insertions, 0 deletions

diff --git a/drivers/gpu/drm/tiny/repaper.c b/drivers/gpu/drm/tiny/repaper.c
new file mode 100644
index 000000000000..76d179200775
--- /dev/null
+++ b/drivers/gpu/drm/tiny/repaper.c
@@ -0,0 +1,1212 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * DRM driver for Pervasive Displays RePaper branded e-ink panels
+ *
+ * Copyright 2013-2017 Pervasive Displays, Inc.
+ * Copyright 2017 Noralf Trønnes
+ *
+ * The driver supports:
+ * Material Film: Aurora Mb (V231)
+ * Driver IC: G2 (eTC)
+ *
+ * The controller code was taken from the userspace driver:
+ * https://github.com/repaper/gratis
+ */
+
+#include <linux/delay.h>
+#include <linux/dma-buf.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/sched/clock.h>
+#include <linux/spi/spi.h>
+#include <linux/thermal.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_rect.h>
+#include <drm/drm_vblank.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#define REPAPER_RID_G2_COG_ID	0x12
+
+enum repaper_model {
+	E1144CS021 = 1,
+	E1190CS021,
+	E2200CS021,
+	E2271CS021,
+};
+
+enum repaper_stage {         /* Image pixel -> Display pixel */
+	REPAPER_COMPENSATE,  /* B -> W, W -> B (Current Image) */
+	REPAPER_WHITE,       /* B -> N, W -> W (Current Image) */
+	REPAPER_INVERSE,     /* B -> N, W -> B (New Image) */
+	REPAPER_NORMAL       /* B -> B, W -> W (New Image) */
+};
+
+enum repaper_epd_border_byte {
+	REPAPER_BORDER_BYTE_NONE,
+	REPAPER_BORDER_BYTE_ZERO,
+	REPAPER_BORDER_BYTE_SET,
+};
+
+struct repaper_epd {
+	struct drm_device drm;
+	struct drm_simple_display_pipe pipe;
+	const struct drm_display_mode *mode;
+	struct drm_connector connector;
+	struct spi_device *spi;
+
+	struct gpio_desc *panel_on;
+	struct gpio_desc *border;
+	struct gpio_desc *discharge;
+	struct gpio_desc *reset;
+	struct gpio_desc *busy;
+
+	struct thermal_zone_device *thermal;
+
+	unsigned int height;
+	unsigned int width;
+	unsigned int bytes_per_scan;
+	const u8 *channel_select;
+	unsigned int stage_time;
+	unsigned int factored_stage_time;
+	bool middle_scan;
+	bool pre_border_byte;
+	enum repaper_epd_border_byte border_byte;
+
+	u8 *line_buffer;
+	void *current_frame;
+
+	bool enabled;
+	bool cleared;
+	bool partial;
+};
+
+static inline struct repaper_epd *drm_to_epd(struct drm_device *drm)
+{
+	return container_of(drm, struct repaper_epd, drm);
+}
+
+static int repaper_spi_transfer(struct spi_device *spi, u8 header,
+				const void *tx, void *rx, size_t len)
+{
+	void *txbuf = NULL, *rxbuf = NULL;
+	struct spi_transfer tr[2] = {};
+	u8 *headerbuf;
+	int ret;
+
+	headerbuf = kmalloc(1, GFP_KERNEL);
+	if (!headerbuf)
+		return -ENOMEM;
+
+	headerbuf[0] = header;
+	tr[0].tx_buf = headerbuf;
+	tr[0].len = 1;
+
+	/* Stack allocated tx? */
+	if (tx && len <= 32) {
+		txbuf = kmemdup(tx, len, GFP_KERNEL);
+		if (!txbuf) {
+			ret = -ENOMEM;
+			goto out_free;
+		}
+	}
+
+	if (rx) {
+		rxbuf = kmalloc(len, GFP_KERNEL);
+		if (!rxbuf) {
+			ret = -ENOMEM;
+			goto out_free;
+		}
+	}
+
+	tr[1].tx_buf = txbuf ? txbuf : tx;
+	tr[1].rx_buf = rxbuf;
+	tr[1].len = len;
+
+	ndelay(80);
+	ret = spi_sync_transfer(spi, tr, 2);
+	if (rx && !ret)
+		memcpy(rx, rxbuf, len);
+
+out_free:
+	kfree(headerbuf);
+	kfree(txbuf);
+	kfree(rxbuf);
+
+	return ret;
+}
+
+static int repaper_write_buf(struct spi_device *spi, u8 reg,
+			     const u8 *buf, size_t len)
+{
+	int ret;
+
+	ret = repaper_spi_transfer(spi, 0x70, &reg, NULL, 1);
+	if (ret)
+		return ret;
+
+	return repaper_spi_transfer(spi, 0x72, buf, NULL, len);
+}
+
+static int repaper_write_val(struct spi_device *spi, u8 reg, u8 val)
+{
+	return repaper_write_buf(spi, reg, &val, 1);
+}
+
+static int repaper_read_val(struct spi_device *spi, u8 reg)
+{
+	int ret;
+	u8 val;
+
+	ret = repaper_spi_transfer(spi, 0x70, &reg, NULL, 1);
+	if (ret)
+		return ret;
+
+	ret = repaper_spi_transfer(spi, 0x73, NULL, &val, 1);
+
+	return ret ? ret : val;
+}
+
+static int repaper_read_id(struct spi_device *spi)
+{
+	int ret;
+	u8 id;
+
+	ret = repaper_spi_transfer(spi, 0x71, NULL, &id, 1);
+
+	return ret ? ret : id;
+}
+
+static void repaper_spi_mosi_low(struct spi_device *spi)
+{
+	const u8 buf[1] = { 0 };
+
+	spi_write(spi, buf, 1);
+}
+
+/* pixels on display are numbered from 1 so even is actually bits 1,3,5,... */
+static void repaper_even_pixels(struct repaper_epd *epd, u8 **pp,
+				const u8 *data, u8 fixed_value, const u8 *mask,
+				enum repaper_stage stage)
+{
+	unsigned int b;
+
+	for (b = 0; b < (epd->width / 8); b++) {
+		if (data) {
+			u8 pixels = data[b] & 0xaa;
+			u8 pixel_mask = 0xff;
+			u8 p1, p2, p3, p4;
+
+			if (mask) {
+				pixel_mask = (mask[b] ^ pixels) & 0xaa;
+				pixel_mask |= pixel_mask >> 1;
+			}
+
+			switch (stage) {
+			case REPAPER_COMPENSATE: /* B -> W, W -> B (Current) */
+				pixels = 0xaa | ((pixels ^ 0xaa) >> 1);
+				break;
+			case REPAPER_WHITE:      /* B -> N, W -> W (Current) */
+				pixels = 0x55 + ((pixels ^ 0xaa) >> 1);
+				break;
+			case REPAPER_INVERSE:    /* B -> N, W -> B (New) */
+				pixels = 0x55 | (pixels ^ 0xaa);
+				break;
+			case REPAPER_NORMAL:     /* B -> B, W -> W (New) */
+				pixels = 0xaa | (pixels >> 1);
+				break;
+			}
+
+			pixels = (pixels & pixel_mask) | (~pixel_mask & 0x55);
+			p1 = (pixels >> 6) & 0x03;
+			p2 = (pixels >> 4) & 0x03;
+			p3 = (pixels >> 2) & 0x03;
+			p4 = (pixels >> 0) & 0x03;
+			pixels = (p1 << 0) | (p2 << 2) | (p3 << 4) | (p4 << 6);
+			*(*pp)++ = pixels;
+		} else {
+			*(*pp)++ = fixed_value;
+		}
+	}
+}
+
+/* pixels on display are numbered from 1 so odd is actually bits 0,2,4,... */
+static void repaper_odd_pixels(struct repaper_epd *epd, u8 **pp,
+			       const u8 *data, u8 fixed_value, const u8 *mask,
+			       enum repaper_stage stage)
+{
+	unsigned int b;
+
+	for (b = epd->width / 8; b > 0; b--) {
+		if (data) {
+			u8 pixels = data[b - 1] & 0x55;
+			u8 pixel_mask = 0xff;
+
+			if (mask) {
+				pixel_mask = (mask[b - 1] ^ pixels) & 0x55;
+				pixel_mask |= pixel_mask << 1;
+			}
+
+			switch (stage) {
+			case REPAPER_COMPENSATE: /* B -> W, W -> B (Current) */
+				pixels = 0xaa | (pixels ^ 0x55);
+				break;
+			case REPAPER_WHITE:      /* B -> N, W -> W (Current) */
+				pixels = 0x55 + (pixels ^ 0x55);
+				break;
+			case REPAPER_INVERSE:    /* B -> N, W -> B (New) */
+				pixels = 0x55 | ((pixels ^ 0x55) << 1);
+				break;
+			case REPAPER_NORMAL:     /* B -> B, W -> W (New) */
+				pixels = 0xaa | pixels;
+				break;
+			}
+
+			pixels = (pixels & pixel_mask) | (~pixel_mask & 0x55);
+			*(*pp)++ = pixels;
+		} else {
+			*(*pp)++ = fixed_value;
+		}
+	}
+}
+
+/* interleave bits: (byte)76543210 -> (16 bit).7.6.5.4.3.2.1 */
+static inline u16 repaper_interleave_bits(u16 value)
+{
+	value = (value | (value << 4)) & 0x0f0f;
+	value = (value | (value << 2)) & 0x3333;
+	value = (value | (value << 1)) & 0x5555;
+
+	return value;
+}
+
+/* pixels on display are numbered from 1 */
+static void repaper_all_pixels(struct repaper_epd *epd, u8 **pp,
+			       const u8 *data, u8 fixed_value, const u8 *mask,
+			       enum repaper_stage stage)
+{
+	unsigned int b;
+
+	for (b = epd->width / 8; b > 0; b--) {
+		if (data) {
+			u16 pixels = repaper_interleave_bits(data[b - 1]);
+			u16 pixel_mask = 0xffff;
+
+			if (mask) {
+				pixel_mask = repaper_interleave_bits(mask[b - 1]);
+
+				pixel_mask = (pixel_mask ^ pixels) & 0x5555;
+				pixel_mask |= pixel_mask << 1;
+			}
+
+			switch (stage) {
+			case REPAPER_COMPENSATE: /* B -> W, W -> B (Current) */
+				pixels = 0xaaaa | (pixels ^ 0x5555);
+				break;
+			case REPAPER_WHITE:      /* B -> N, W -> W (Current) */
+				pixels = 0x5555 + (pixels ^ 0x5555);
+				break;
+			case REPAPER_INVERSE:    /* B -> N, W -> B (New) */
+				pixels = 0x5555 | ((pixels ^ 0x5555) << 1);
+				break;
+			case REPAPER_NORMAL:     /* B -> B, W -> W (New) */
+				pixels = 0xaaaa | pixels;
+				break;
+			}
+
+			pixels = (pixels & pixel_mask) | (~pixel_mask & 0x5555);
+			*(*pp)++ = pixels >> 8;
+			*(*pp)++ = pixels;
+		} else {
+			*(*pp)++ = fixed_value;
+			*(*pp)++ = fixed_value;
+		}
+	}
+}
+
+/* output one line of scan and data bytes to the display */
+static void repaper_one_line(struct repaper_epd *epd, unsigned int line,
+			     const u8 *data, u8 fixed_value, const u8 *mask,
+			     enum repaper_stage stage)
+{
+	u8 *p = epd->line_buffer;
+	unsigned int b;
+
+	repaper_spi_mosi_low(epd->spi);
+
+	if (epd->pre_border_byte)
+		*p++ = 0x00;
+
+	if (epd->middle_scan) {
+		/* data bytes */
+		repaper_odd_pixels(epd, &p, data, fixed_value, mask, stage);
+
+		/* scan line */
+		for (b = epd->bytes_per_scan; b > 0; b--) {
+			if (line / 4 == b - 1)
+				*p++ = 0x03 << (2 * (line & 0x03));
+			else
+				*p++ = 0x00;
+		}
+
+		/* data bytes */
+		repaper_even_pixels(epd, &p, data, fixed_value, mask, stage);
+	} else {
+		/*
+		 * even scan line, but as lines on display are numbered from 1,
+		 * line: 1,3,5,...
+		 */
+		for (b = 0; b < epd->bytes_per_scan; b++) {
+			if (0 != (line & 0x01) && line / 8 == b)
+				*p++ = 0xc0 >> (line & 0x06);
+			else
+				*p++ = 0x00;
+		}
+
+		/* data bytes */
+		repaper_all_pixels(epd, &p, data, fixed_value, mask, stage);
+
+		/*
+		 * odd scan line, but as lines on display are numbered from 1,
+		 * line: 0,2,4,6,...
+		 */
+		for (b = epd->bytes_per_scan; b > 0; b--) {
+			if (0 == (line & 0x01) && line / 8 == b - 1)
+				*p++ = 0x03 << (line & 0x06);
+			else
+				*p++ = 0x00;
+		}
+	}
+
+	switch (epd->border_byte) {
+	case REPAPER_BORDER_BYTE_NONE:
+		break;
+
+	case REPAPER_BORDER_BYTE_ZERO:
+		*p++ = 0x00;
+		break;
+
+	case REPAPER_BORDER_BYTE_SET:
+		switch (stage) {
+		case REPAPER_COMPENSATE:
+		case REPAPER_WHITE:
+		case REPAPER_INVERSE:
+			*p++ = 0x00;
+			break;
+		case REPAPER_NORMAL:
+			*p++ = 0xaa;
+			break;
+		}
+		break;
+	}
+
+	repaper_write_buf(epd->spi, 0x0a, epd->line_buffer,
+			  p - epd->line_buffer);
+
+	/* Output data to panel */
+	repaper_write_val(epd->spi, 0x02, 0x07);
+
+	repaper_spi_mosi_low(epd->spi);
+}
+
+static void repaper_frame_fixed(struct repaper_epd *epd, u8 fixed_value,
+				enum repaper_stage stage)
+{
+	unsigned int line;
+
+	for (line = 0; line < epd->height; line++)
+		repaper_one_line(epd, line, NULL, fixed_value, NULL, stage);
+}
+
+static void repaper_frame_data(struct repaper_epd *epd, const u8 *image,
+			       const u8 *mask, enum repaper_stage stage)
+{
+	unsigned int line;
+
+	if (!mask) {
+		for (line = 0; line < epd->height; line++) {
+			repaper_one_line(epd, line,
+					 &image[line * (epd->width / 8)],
+					 0, NULL, stage);
+		}
+	} else {
+		for (line = 0; line < epd->height; line++) {
+			size_t n = line * epd->width / 8;
+
+			repaper_one_line(epd, line, &image[n], 0, &mask[n],
+					 stage);
+		}
+	}
+}
+
+static void repaper_frame_fixed_repeat(struct repaper_epd *epd, u8 fixed_value,
+				       enum repaper_stage stage)
+{
+	u64 start = local_clock();
+	u64 end = start + (epd->factored_stage_time * 1000 * 1000);
+
+	do {
+		repaper_frame_fixed(epd, fixed_value, stage);
+	} while (local_clock() < end);
+}
+
+static void repaper_frame_data_repeat(struct repaper_epd *epd, const u8 *image,
+				      const u8 *mask, enum repaper_stage stage)
+{
+	u64 start = local_clock();
+	u64 end = start + (epd->factored_stage_time * 1000 * 1000);
+
+	do {
+		repaper_frame_data(epd, image, mask, stage);
+	} while (local_clock() < end);
+}
+
+static void repaper_get_temperature(struct repaper_epd *epd)
+{
+	int ret, temperature = 0;
+	unsigned int factor10x;
+
+	if (!epd->thermal)
+		return;
+
+	ret = thermal_zone_get_temp(epd->thermal, &temperature);
+	if (ret) {
+		DRM_DEV_ERROR(&epd->spi->dev, "Failed to get temperature (%d)\n", ret);
+		return;
+	}
+
+	temperature /= 1000;
+
+	if (temperature <= -10)
+		factor10x = 170;
+	else if (temperature <= -5)
+		factor10x = 120;
+	else if (temperature <= 5)
+		factor10x = 80;
+	else if (temperature <= 10)
+		factor10x = 40;
+	else if (temperature <= 15)
+		factor10x = 30;
+	else if (temperature <= 20)
+		factor10x = 20;
+	else if (temperature <= 40)
+		factor10x = 10;
+	else
+		factor10x = 7;
+
+	epd->factored_stage_time = epd->stage_time * factor10x / 10;
+}
+
+static void repaper_gray8_to_mono_reversed(u8 *buf, u32 width, u32 height)
+{
+	u8 *gray8 = buf, *mono = buf;
+	int y, xb, i;
+
+	for (y = 0; y < height; y++)
+		for (xb = 0; xb < width / 8; xb++) {
+			u8 byte = 0x00;
+
+			for (i = 0; i < 8; i++) {
+				int x = xb * 8 + i;
+
+				byte >>= 1;
+				if (gray8[y * width + x] >> 7)
+					byte |= BIT(7);
+			}
+			*mono++ = byte;
+		}
+}
+
+static int repaper_fb_dirty(struct drm_framebuffer *fb)
+{
+	struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
+	struct dma_buf_attachment *import_attach = cma_obj->base.import_attach;
+	struct repaper_epd *epd = drm_to_epd(fb->dev);
+	struct drm_rect clip;
+	int idx, ret = 0;
+	u8 *buf = NULL;
+
+	if (!epd->enabled)
+		return 0;
+
+	if (!drm_dev_enter(fb->dev, &idx))
+		return -ENODEV;
+
+	/* repaper can't do partial updates */
+	clip.x1 = 0;
+	clip.x2 = fb->width;
+	clip.y1 = 0;
+	clip.y2 = fb->height;
+
+	repaper_get_temperature(epd);
+
+	DRM_DEBUG("Flushing [FB:%d] st=%ums\n", fb->base.id,
+		  epd->factored_stage_time);
+
+	buf = kmalloc_array(fb->width, fb->height, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto out_exit;
+	}
+
+	if (import_attach) {
+		ret = dma_buf_begin_cpu_access(import_attach->dmabuf,
+					       DMA_FROM_DEVICE);
+		if (ret)
+			goto out_free;
+	}
+
+	drm_fb_xrgb8888_to_gray8(buf, cma_obj->vaddr, fb, &clip);
+
+	if (import_attach) {
+		ret = dma_buf_end_cpu_access(import_attach->dmabuf,
+					     DMA_FROM_DEVICE);
+		if (ret)
+			goto out_free;
+	}
+
+	repaper_gray8_to_mono_reversed(buf, fb->width, fb->height);
+
+	if (epd->partial) {
+		repaper_frame_data_repeat(epd, buf, epd->current_frame,
+					  REPAPER_NORMAL);
+	} else if (epd->cleared) {
+		repaper_frame_data_repeat(epd, epd->current_frame, NULL,
+					  REPAPER_COMPENSATE);
+		repaper_frame_data_repeat(epd, epd->current_frame, NULL,
+					  REPAPER_WHITE);
+		repaper_frame_data_repeat(epd, buf, NULL, REPAPER_INVERSE);
+		repaper_frame_data_repeat(epd, buf, NULL, REPAPER_NORMAL);
+
+		epd->partial = true;
+	} else {
+		/* Clear display (anything -> white) */
+		repaper_frame_fixed_repeat(epd, 0xff, REPAPER_COMPENSATE);
+		repaper_frame_fixed_repeat(epd, 0xff, REPAPER_WHITE);
+		repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_INVERSE);
+		repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_NORMAL);
+
+		/* Assuming a clear (white) screen output an image */
+		repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_COMPENSATE);
+		repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_WHITE);
+		repaper_frame_data_repeat(epd, buf, NULL, REPAPER_INVERSE);
+		repaper_frame_data_repeat(epd, buf, NULL, REPAPER_NORMAL);
+
+		epd->cleared = true;
+		epd->partial = true;
+	}
+
+	memcpy(epd->current_frame, buf, fb->width * fb->height / 8);
+
+	/*
+	 * An extra frame write is needed if pixels are set in the bottom line,
+	 * or else grey lines rises up from the pixels
+	 */
+	if (epd->pre_border_byte) {
+		unsigned int x;
+
+		for (x = 0; x < (fb->width / 8); x++)
+			if (buf[x + (fb->width * (fb->height - 1) / 8)]) {
+				repaper_frame_data_repeat(epd, buf,
+							  epd->current_frame,
+							  REPAPER_NORMAL);
+				break;
+			}
+	}
+
+out_free:
+	kfree(buf);
+out_exit:
+	drm_dev_exit(idx);
+
+	return ret;
+}
+
+static void power_off(struct repaper_epd *epd)
+{
+	/* Turn off power and all signals */
+	gpiod_set_value_cansleep(epd->reset, 0);
+	gpiod_set_value_cansleep(epd->panel_on, 0);
+	if (epd->border)
+		gpiod_set_value_cansleep(epd->border, 0);
+
+	/* Ensure SPI MOSI and CLOCK are Low before CS Low */
+	repaper_spi_mosi_low(epd->spi);
+
+	/* Discharge pulse */
+	gpiod_set_value_cansleep(epd->discharge, 1);
+	msleep(150);
+	gpiod_set_value_cansleep(epd->discharge, 0);
+}
+
+static void repaper_pipe_enable(struct drm_simple_display_pipe *pipe,
+				struct drm_crtc_state *crtc_state,
+				struct drm_plane_state *plane_state)
+{
+	struct repaper_epd *epd = drm_to_epd(pipe->crtc.dev);
+	struct spi_device *spi = epd->spi;
+	struct device *dev = &spi->dev;
+	bool dc_ok = false;
+	int i, ret, idx;
+
+	if (!drm_dev_enter(pipe->crtc.dev, &idx))
+		return;
+
+	DRM_DEBUG_DRIVER("\n");
+
+	/* Power up sequence */
+	gpiod_set_value_cansleep(epd->reset, 0);
+	gpiod_set_value_cansleep(epd->panel_on, 0);
+	gpiod_set_value_cansleep(epd->discharge, 0);
+	if (epd->border)
+		gpiod_set_value_cansleep(epd->border, 0);
+	repaper_spi_mosi_low(spi);
+	usleep_range(5000, 10000);
+
+	gpiod_set_value_cansleep(epd->panel_on, 1);
+	/*
+	 * This delay comes from the repaper.org userspace driver, it's not
+	 * mentioned in the datasheet.
+	 */
+	usleep_range(10000, 15000);
+	gpiod_set_value_cansleep(epd->reset, 1);
+	if (epd->border)
+		gpiod_set_value_cansleep(epd->border, 1);
+	usleep_range(5000, 10000);
+	gpiod_set_value_cansleep(epd->reset, 0);
+	usleep_range(5000, 10000);
+	gpiod_set_value_cansleep(epd->reset, 1);
+	usleep_range(5000, 10000);
+
+	/* Wait for COG to become ready */
+	for (i = 100; i > 0; i--) {
+		if (!gpiod_get_value_cansleep(epd->busy))
+			break;
+
+		usleep_range(10, 100);
+	}
+
+	if (!i) {
+		DRM_DEV_ERROR(dev, "timeout waiting for panel to become ready.\n");
+		power_off(epd);
+		goto out_exit;
+	}
+
+	repaper_read_id(spi);
+	ret = repaper_read_id(spi);
+	if (ret != REPAPER_RID_G2_COG_ID) {
+		if (ret < 0)
+			dev_err(dev, "failed to read chip (%d)\n", ret);
+		else
+			dev_err(dev, "wrong COG ID 0x%02x\n", ret);
+		power_off(epd);
+		goto out_exit;
+	}
+
+	/* Disable OE */
+	repaper_write_val(spi, 0x02, 0x40);
+
+	ret = repaper_read_val(spi, 0x0f);
+	if (ret < 0 || !(ret & 0x80)) {
+		if (ret < 0)
+			DRM_DEV_ERROR(dev, "failed to read chip (%d)\n", ret);
+		else
+			DRM_DEV_ERROR(dev, "panel is reported broken\n");
+		power_off(epd);
+		goto out_exit;
+	}
+
+	/* Power saving mode */
+	repaper_write_val(spi, 0x0b, 0x02);
+	/* Channel select */
+	repaper_write_buf(spi, 0x01, epd->channel_select, 8);
+	/* High power mode osc */
+	repaper_write_val(spi, 0x07, 0xd1);
+	/* Power setting */
+	repaper_write_val(spi, 0x08, 0x02);
+	/* Vcom level */
+	repaper_write_val(spi, 0x09, 0xc2);
+	/* Power setting */
+	repaper_write_val(spi, 0x04, 0x03);
+	/* Driver latch on */
+	repaper_write_val(spi, 0x03, 0x01);
+	/* Driver latch off */
+	repaper_write_val(spi, 0x03, 0x00);
+	usleep_range(5000, 10000);
+
+	/* Start chargepump */
+	for (i = 0; i < 4; ++i) {
+		/* Charge pump positive voltage on - VGH/VDL on */
+		repaper_write_val(spi, 0x05, 0x01);
+		msleep(240);
+
+		/* Charge pump negative voltage on - VGL/VDL on */
+		repaper_write_val(spi, 0x05, 0x03);
+		msleep(40);
+
+		/* Charge pump Vcom on - Vcom driver on */
+		repaper_write_val(spi, 0x05, 0x0f);
+		msleep(40);
+
+		/* check DC/DC */
+		ret = repaper_read_val(spi, 0x0f);
+		if (ret < 0) {
+			DRM_DEV_ERROR(dev, "failed to read chip (%d)\n", ret);
+			power_off(epd);
+			goto out_exit;
+		}
+
+		if (ret & 0x40) {
+			dc_ok = true;
+			break;
+		}
+	}
+
+	if (!dc_ok) {
+		DRM_DEV_ERROR(dev, "dc/dc failed\n");
+		power_off(epd);
+		goto out_exit;
+	}
+
+	/*
+	 * Output enable to disable
+	 * The userspace driver sets this to 0x04, but the datasheet says 0x06
+	 */
+	repaper_write_val(spi, 0x02, 0x04);
+
+	epd->enabled = true;
+	epd->partial = false;
+out_exit:
+	drm_dev_exit(idx);
+}
+
+static void repaper_pipe_disable(struct drm_simple_display_pipe *pipe)
+{
+	struct repaper_epd *epd = drm_to_epd(pipe->crtc.dev);
+	struct spi_device *spi = epd->spi;
+	unsigned int line;
+
+	/*
+	 * This callback is not protected by drm_dev_enter/exit since we want to
+	 * turn off the display on regular driver unload. It's highly unlikely
+	 * that the underlying SPI controller is gone should this be called after
+	 * unplug.
+	 */
+
+	if (!epd->enabled)
+		return;
+
+	DRM_DEBUG_DRIVER("\n");
+
+	epd->enabled = false;
+
+	/* Nothing frame */
+	for (line = 0; line < epd->height; line++)
+		repaper_one_line(epd, 0x7fffu, NULL, 0x00, NULL,
+				 REPAPER_COMPENSATE);
+
+	/* 2.7" */
+	if (epd->border) {
+		/* Dummy line */
+		repaper_one_line(epd, 0x7fffu, NULL, 0x00, NULL,
+				 REPAPER_COMPENSATE);
+		msleep(25);
+		gpiod_set_value_cansleep(epd->border, 0);
+		msleep(200);
+		gpiod_set_value_cansleep(epd->border, 1);
+	} else {
+		/* Border dummy line */
+		repaper_one_line(epd, 0x7fffu, NULL, 0x00, NULL,
+				 REPAPER_NORMAL);
+		msleep(200);
+	}
+
+	/* not described in datasheet */
+	repaper_write_val(spi, 0x0b, 0x00);
+	/* Latch reset turn on */
+	repaper_write_val(spi, 0x03, 0x01);
+	/* Power off charge pump Vcom */
+	repaper_write_val(spi, 0x05, 0x03);
+	/* Power off charge pump neg voltage */
+	repaper_write_val(spi, 0x05, 0x01);
+	msleep(120);
+	/* Discharge internal */
+	repaper_write_val(spi, 0x04, 0x80);
+	/* turn off all charge pumps */
+	repaper_write_val(spi, 0x05, 0x00);
+	/* Turn off osc */
+	repaper_write_val(spi, 0x07, 0x01);
+	msleep(50);
+
+	power_off(epd);
+}
+
+static void repaper_pipe_update(struct drm_simple_display_pipe *pipe,
+				struct drm_plane_state *old_state)
+{
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_crtc *crtc = &pipe->crtc;
+	struct drm_rect rect;
+
+	if (drm_atomic_helper_damage_merged(old_state, state, &rect))
+		repaper_fb_dirty(state->fb);
+
+	if (crtc->state->event) {
+		spin_lock_irq(&crtc->dev->event_lock);
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		spin_unlock_irq(&crtc->dev->event_lock);
+		crtc->state->event = NULL;
+	}
+}
+
+static const struct drm_simple_display_pipe_funcs repaper_pipe_funcs = {
+	.enable = repaper_pipe_enable,
+	.disable = repaper_pipe_disable,
+	.update = repaper_pipe_update,
+	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+static int repaper_connector_get_modes(struct drm_connector *connector)
+{
+	struct repaper_epd *epd = drm_to_epd(connector->dev);
+	struct drm_display_mode *mode;
+
+	mode = drm_mode_duplicate(connector->dev, epd->mode);
+	if (!mode) {
+		DRM_ERROR("Failed to duplicate mode\n");
+		return 0;
+	}
+
+	drm_mode_set_name(mode);
+	mode->type |= DRM_MODE_TYPE_PREFERRED;
+	drm_mode_probed_add(connector, mode);
+
+	connector->display_info.width_mm = mode->width_mm;
+	connector->display_info.height_mm = mode->height_mm;
+
+	return 1;
+}
+
+static const struct drm_connector_helper_funcs repaper_connector_hfuncs = {
+	.get_modes = repaper_connector_get_modes,
+};
+
+static const struct drm_connector_funcs repaper_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 repaper_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static void repaper_release(struct drm_device *drm)
+{
+	struct repaper_epd *epd = drm_to_epd(drm);
+
+	DRM_DEBUG_DRIVER("\n");
+
+	drm_mode_config_cleanup(drm);
+	drm_dev_fini(drm);
+	kfree(epd);
+}
+
+static const uint32_t repaper_formats[] = {
+	DRM_FORMAT_XRGB8888,
+};
+
+static const struct drm_display_mode repaper_e1144cs021_mode = {
+	DRM_SIMPLE_MODE(128, 96, 29, 22),
+};
+
+static const u8 repaper_e1144cs021_cs[] = { 0x00, 0x00, 0x00, 0x00,
+					    0x00, 0x0f, 0xff, 0x00 };
+
+static const struct drm_display_mode repaper_e1190cs021_mode = {
+	DRM_SIMPLE_MODE(144, 128, 36, 32),
+};
+
+static const u8 repaper_e1190cs021_cs[] = { 0x00, 0x00, 0x00, 0x03,
+					    0xfc, 0x00, 0x00, 0xff };
+
+static const struct drm_display_mode repaper_e2200cs021_mode = {
+	DRM_SIMPLE_MODE(200, 96, 46, 22),
+};
+
+static const u8 repaper_e2200cs021_cs[] = { 0x00, 0x00, 0x00, 0x00,
+					    0x01, 0xff, 0xe0, 0x00 };
+
+static const struct drm_display_mode repaper_e2271cs021_mode = {
+	DRM_SIMPLE_MODE(264, 176, 57, 38),
+};
+
+static const u8 repaper_e2271cs021_cs[] = { 0x00, 0x00, 0x00, 0x7f,
+					    0xff, 0xfe, 0x00, 0x00 };
+
+DEFINE_DRM_GEM_CMA_FOPS(repaper_fops);
+
+static struct drm_driver repaper_driver = {
+	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+	.fops			= &repaper_fops,
+	.release		= repaper_release,
+	DRM_GEM_CMA_VMAP_DRIVER_OPS,
+	.name			= "repaper",
+	.desc			= "Pervasive Displays RePaper e-ink panels",
+	.date			= "20170405",
+	.major			= 1,
+	.minor			= 0,
+};
+
+static const struct of_device_id repaper_of_match[] = {
+	{ .compatible = "pervasive,e1144cs021", .data = (void *)E1144CS021 },
+	{ .compatible = "pervasive,e1190cs021", .data = (void *)E1190CS021 },
+	{ .compatible = "pervasive,e2200cs021", .data = (void *)E2200CS021 },
+	{ .compatible = "pervasive,e2271cs021", .data = (void *)E2271CS021 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, repaper_of_match);
+
+static const struct spi_device_id repaper_id[] = {
+	{ "e1144cs021", E1144CS021 },
+	{ "e1190cs021", E1190CS021 },
+	{ "e2200cs021", E2200CS021 },
+	{ "e2271cs021", E2271CS021 },
+	{ },
+};
+MODULE_DEVICE_TABLE(spi, repaper_id);
+
+static int repaper_probe(struct spi_device *spi)
+{
+	const struct drm_display_mode *mode;
+	const struct spi_device_id *spi_id;
+	const struct of_device_id *match;
+	struct device *dev = &spi->dev;
+	enum repaper_model model;
+	const char *thermal_zone;
+	struct repaper_epd *epd;
+	size_t line_buffer_size;
+	struct drm_device *drm;
+	int ret;
+
+	match = of_match_device(repaper_of_match, dev);
+	if (match) {
+		model = (enum repaper_model)match->data;
+	} else {
+		spi_id = spi_get_device_id(spi);
+		model = spi_id->driver_data;
+	}
+
+	/* The SPI device is used to allocate dma memory */
+	if (!dev->coherent_dma_mask) {
+		ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
+		if (ret) {
+			dev_warn(dev, "Failed to set dma mask %d\n", ret);
+			return ret;
+		}
+	}
+
+	epd = kzalloc(sizeof(*epd), GFP_KERNEL);
+	if (!epd)
+		return -ENOMEM;
+
+	drm = &epd->drm;
+
+	ret = devm_drm_dev_init(dev, drm, &repaper_driver);
+	if (ret) {
+		kfree(epd);
+		return ret;
+	}
+
+	drm_mode_config_init(drm);
+	drm->mode_config.funcs = &repaper_mode_config_funcs;
+
+	epd->spi = spi;
+
+	epd->panel_on = devm_gpiod_get(dev, "panel-on", GPIOD_OUT_LOW);
+	if (IS_ERR(epd->panel_on)) {
+		ret = PTR_ERR(epd->panel_on);
+		if (ret != -EPROBE_DEFER)
+			DRM_DEV_ERROR(dev, "Failed to get gpio 'panel-on'\n");
+		return ret;
+	}
+
+	epd->discharge = devm_gpiod_get(dev, "discharge", GPIOD_OUT_LOW);
+	if (IS_ERR(epd->discharge)) {
+		ret = PTR_ERR(epd->discharge);
+		if (ret != -EPROBE_DEFER)
+			DRM_DEV_ERROR(dev, "Failed to get gpio 'discharge'\n");
+		return ret;
+	}
+
+	epd->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(epd->reset)) {
+		ret = PTR_ERR(epd->reset);
+		if (ret != -EPROBE_DEFER)
+			DRM_DEV_ERROR(dev, "Failed to get gpio 'reset'\n");
+		return ret;
+	}
+
+	epd->busy = devm_gpiod_get(dev, "busy", GPIOD_IN);
+	if (IS_ERR(epd->busy)) {
+		ret = PTR_ERR(epd->busy);
+		if (ret != -EPROBE_DEFER)
+			DRM_DEV_ERROR(dev, "Failed to get gpio 'busy'\n");
+		return ret;
+	}
+
+	if (!device_property_read_string(dev, "pervasive,thermal-zone",
+					 &thermal_zone)) {
+		epd->thermal = thermal_zone_get_zone_by_name(thermal_zone);
+		if (IS_ERR(epd->thermal)) {
+			DRM_DEV_ERROR(dev, "Failed to get thermal zone: %s\n", thermal_zone);
+			return PTR_ERR(epd->thermal);
+		}
+	}
+
+	switch (model) {
+	case E1144CS021:
+		mode = &repaper_e1144cs021_mode;
+		epd->channel_select = repaper_e1144cs021_cs;
+		epd->stage_time = 480;
+		epd->bytes_per_scan = 96 / 4;
+		epd->middle_scan = true; /* data-scan-data */
+		epd->pre_border_byte = false;
+		epd->border_byte = REPAPER_BORDER_BYTE_ZERO;
+		break;
+
+	case E1190CS021:
+		mode = &repaper_e1190cs021_mode;
+		epd->channel_select = repaper_e1190cs021_cs;
+		epd->stage_time = 480;
+		epd->bytes_per_scan = 128 / 4 / 2;
+		epd->middle_scan = false; /* scan-data-scan */
+		epd->pre_border_byte = false;
+		epd->border_byte = REPAPER_BORDER_BYTE_SET;
+		break;
+
+	case E2200CS021:
+		mode = &repaper_e2200cs021_mode;
+		epd->channel_select = repaper_e2200cs021_cs;
+		epd->stage_time = 480;
+		epd->bytes_per_scan = 96 / 4;
+		epd->middle_scan = true; /* data-scan-data */
+		epd->pre_border_byte = true;
+		epd->border_byte = REPAPER_BORDER_BYTE_NONE;
+		break;
+
+	case E2271CS021:
+		epd->border = devm_gpiod_get(dev, "border", GPIOD_OUT_LOW);
+		if (IS_ERR(epd->border)) {
+			ret = PTR_ERR(epd->border);
+			if (ret != -EPROBE_DEFER)
+				DRM_DEV_ERROR(dev, "Failed to get gpio 'border'\n");
+			return ret;
+		}
+
+		mode = &repaper_e2271cs021_mode;
+		epd->channel_select = repaper_e2271cs021_cs;
+		epd->stage_time = 630;
+		epd->bytes_per_scan = 176 / 4;
+		epd->middle_scan = true; /* data-scan-data */
+		epd->pre_border_byte = true;
+		epd->border_byte = REPAPER_BORDER_BYTE_NONE;
+		break;
+
+	default:
+		return -ENODEV;
+	}
+
+	epd->mode = mode;
+	epd->width = mode->hdisplay;
+	epd->height = mode->vdisplay;
+	epd->factored_stage_time = epd->stage_time;
+
+	line_buffer_size = 2 * epd->width / 8 + epd->bytes_per_scan + 2;
+	epd->line_buffer = devm_kzalloc(dev, line_buffer_size, GFP_KERNEL);
+	if (!epd->line_buffer)
+		return -ENOMEM;
+
+	epd->current_frame = devm_kzalloc(dev, epd->width * epd->height / 8,
+					  GFP_KERNEL);
+	if (!epd->current_frame)
+		return -ENOMEM;
+
+	drm->mode_config.min_width = mode->hdisplay;
+	drm->mode_config.max_width = mode->hdisplay;
+	drm->mode_config.min_height = mode->vdisplay;
+	drm->mode_config.max_height = mode->vdisplay;
+
+	drm_connector_helper_add(&epd->connector, &repaper_connector_hfuncs);
+	ret = drm_connector_init(drm, &epd->connector, &repaper_connector_funcs,
+				 DRM_MODE_CONNECTOR_SPI);
+	if (ret)
+		return ret;
+
+	ret = drm_simple_display_pipe_init(drm, &epd->pipe, &repaper_pipe_funcs,
+					   repaper_formats, ARRAY_SIZE(repaper_formats),
+					   NULL, &epd->connector);
+	if (ret)
+		return ret;
+
+	drm_mode_config_reset(drm);
+
+	ret = drm_dev_register(drm, 0);
+	if (ret)
+		return ret;
+
+	spi_set_drvdata(spi, drm);
+
+	DRM_DEBUG_DRIVER("SPI speed: %uMHz\n", spi->max_speed_hz / 1000000);
+
+	drm_fbdev_generic_setup(drm, 0);
+
+	return 0;
+}
+
+static int repaper_remove(struct spi_device *spi)
+{
+	struct drm_device *drm = spi_get_drvdata(spi);
+
+	drm_dev_unplug(drm);
+	drm_atomic_helper_shutdown(drm);
+
+	return 0;
+}
+
+static void repaper_shutdown(struct spi_device *spi)
+{
+	drm_atomic_helper_shutdown(spi_get_drvdata(spi));
+}
+
+static struct spi_driver repaper_spi_driver = {
+	.driver = {
+		.name = "repaper",
+		.owner = THIS_MODULE,
+		.of_match_table = repaper_of_match,
+	},
+	.id_table = repaper_id,
+	.probe = repaper_probe,
+	.remove = repaper_remove,
+	.shutdown = repaper_shutdown,
+};
+module_spi_driver(repaper_spi_driver);
+
+MODULE_DESCRIPTION("Pervasive Displays RePaper DRM driver");
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");