path: root/drivers/gpu/drm/tiny/repaper.c

// 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/gpio/consumer.h>
#include <linux/module.h>
#include <linux/property.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_dma_helper.h>
#include <drm/drm_fbdev_dma.h>
#include <drm/drm_format_helper.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_dma_helper.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_managed.h>
#include <drm/drm_modes.h>
#include <drm/drm_rect.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_simple_kms_helper.h>

#define REPAPER_RID_G2_COG_ID	0x12

enum repaper_model {
	/* 0 is reserved to avoid clashing with NULL */
	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 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