path: root/drivers/gpu/drm/tiny/sharp-memory.c

// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_client_setup.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_probe_helper.h>
#include <drm/drm_rect.h>
#include <linux/bitrev.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/kthread.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pwm.h>
#include <linux/spi/spi.h>

#define SHARP_MODE_PERIOD 8
#define SHARP_ADDR_PERIOD 8
#define SHARP_DUMMY_PERIOD 8

#define SHARP_MEMORY_DISPLAY_MAINTAIN_MODE 0
#define SHARP_MEMORY_DISPLAY_UPDATE_MODE 1
#define SHARP_MEMORY_DISPLAY_CLEAR_MODE 4

enum sharp_memory_model {
	LS010B7DH04,
	LS011B7DH03,
	LS012B7DD01,
	LS013B7DH03,
	LS013B7DH05,
	LS018B7DH02,
	LS027B7DH01,
	LS027B7DH01A,
	LS032B7DD02,
	LS044Q7DH01,
};

enum sharp_memory_vcom_mode {
	SHARP_MEMORY_SOFTWARE_VCOM,
	SHARP_MEMORY_EXTERNAL_VCOM,
	SHARP_MEMORY_PWM_VCOM
};

struct sharp_memory_device {
	struct drm_device drm;
	struct spi_device *spi;

	const struct drm_display_mode *mode;

	struct drm_crtc crtc;
	struct drm_plane plane;
	struct drm_encoder encoder;
	struct drm_connector connector;

	struct gpio_desc *enable_gpio;

	struct task_struct *sw_vcom_signal;
	struct pwm_device *pwm_vcom_signal;

	enum sharp_memory_vcom_mode vcom_mode;
	u8 vcom;

	u32 pitch;
	u32 tx_buffer_size;
	u8 *tx_buffer;

	/* When vcom_mode == "software" a kthread is used to periodically send a
	 * 'maintain display' message over spi. This mutex ensures tx_buffer access
	 * and spi bus usage is synchronized in this case.
	 */
	struct mutex tx_mutex;
};

static inline int sharp_memory_spi_write(struct spi_device *spi, void *buf, size_t len)
{
	/* Reverse the bit order */
	for (u8 *b = buf; b < ((u8 *)buf) + len; ++b)
		*b = bitrev8(*b);

	return spi_write(spi, buf, len);
}

static inline struct sharp_memory_device *drm_to_sharp_memory_device(struct drm_device *drm)
{
	return container_of(drm, struct sharp_memory_device, drm);
}

DEFINE_DRM_GEM_DMA_FOPS(sharp_memory_fops);

static const struct drm_driver sharp_memory_drm_driver = {
	.driver_features	= DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
	.fops			= &sharp_memory_fops,
	DRM_GEM_DMA_DRIVER_OPS_VMAP,
	DRM_FBDEV_DMA_DRIVER_OPS,
	.name			= "sharp_memory_display",
	.desc			= "Sharp Display Memory LCD",
	.date			= "20231129",
	.major			= 1,
	.minor			= 0,
};

static inline void sharp_memory_set_tx_buffer_mode(u8 *buffer, u8 mode, u8 vcom)
{
	*buffer = mode | (vcom << 1);
}

static inline void sharp_memory_set_tx_buffer_addresses(u8 *buffer,
							struct drm_rect clip,
							u32 pitch)
{
	for (u32 line = 0; line < clip.y2; ++line)
		buffer[line * pitch] = line + 1;
}

static void sharp_memory_set_tx_buffer_data(u8 *buffer,
					    struct drm_framebuffer *fb,
					    struct drm_rect clip,
					    u32 pitch,
					    struct drm_format_conv_state *fmtcnv_state)
{
	int ret;
	struct iosys_map dst, vmap;
	struct drm_gem_dma_object *dma_obj = drm_fb_dma_get_gem_obj(fb, 0);

	ret = drm_gem_fb_begin_cpu_access(fb, DMA_FROM_DEVICE);
	if (ret)
		return;

	iosys_map_set_vaddr(&dst, buffer);
	iosys_map_set_vaddr(&vmap, dma_obj->vaddr);

	drm_fb_xrgb8888_to_mono(&dst, &pitch, &vmap, fb, &clip, fmtcnv_state);

	drm_gem_fb_end_cpu_access(fb, DMA_FROM_DEVICE);
}

static int sharp_memory_update_display(struct sharp_memory_device *smd,
				       struct drm_framebuffer *fb,
				       struct drm_rect clip,
				       struct drm_format_conv_state *fmtcnv_state)
{
	int ret;
	u32 pitch = smd->pitch;
	u8 vcom = smd->vcom;
	u8 *tx_buffer = smd->tx_buffer;
	u32 tx_buffer_size = smd->tx_buffer_size;

	mutex_lock(&smd->tx_mutex);

	/* Populate the transmit buffer with frame data */
	sharp_memory_set_tx_buffer_mode(&tx_buffer[0],
					SHARP_MEMORY_DISPLAY_UPDATE_MODE, vcom);
	sharp_memory_set_tx_buffer_addresses(&tx_buffer[1], clip, pitch);
	sharp_memory_set_tx_buffer_data(&tx_buffer[2], fb, clip, pitch, fmtcnv_state);

	ret = sharp_memory_spi_write(smd->spi, tx_buffer, tx_buffer_size);

	mutex_unlock(&smd->tx_mutex);

	return ret;
}

static int sharp_memory_maintain_display(struct sharp_memory_device *smd)
{
	int ret;
	u8 vcom = smd->vcom;
	u8 *tx_buffer = smd->tx_buffer;

	mutex_lock(&smd->tx_mutex);

	sharp_memory_set_tx_buffer_mode(&tx_buffer[0], SHARP_MEMORY_DISPLAY_MAINTAIN_MODE, vcom);
	tx_buffer[1] = 0; /* Write dummy data */
	ret = sharp_memory_spi_write(smd->spi, tx_buffer, 2);

	mutex_unlock(&smd->tx_mutex);

	return ret;
}

static int sharp_memory_clear_display(struct sharp_memory_device *smd)
{
	int ret;
	u8 vcom = smd->vcom;
	u8 *tx_buffer = smd->tx_buffer;

	mutex_lock(&smd->tx_mutex);

	sharp_memory_set_tx_buffer_mode(&tx_buffer[0], SHARP_MEMORY_DISPLAY_CLEAR_MODE, vcom);
	tx_buffer[1] = 0; /* write dummy data */
	ret = sharp_memory_spi_write(smd->spi, tx_buffer, 2);

	mutex_unlock(&smd->tx_mutex);

	return ret;
}

static void sharp_memory_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect,
				  struct drm_format_conv_state *fmtconv_state)
{
	struct drm_rect clip;
	struct sharp_memory_device *smd = drm_to_sharp_memory_device(fb->dev);

	/* Always update a full line regardless of what is dirty */
	clip.x1 = 0;
	clip.x2 = fb->width;
	clip.y1 = rect->y1;
	clip.y2 = rect->y2;

	sharp_memory_update_display(smd, fb, clip, fmtconv_state);
}

static int sharp_memory_plane_atomic_check(struct drm_plane *plane,
					   struct drm_atomic_state *state)
{
	struct drm_plane_state *plane_state = drm_atomic_get_new_plane_state(state, plane);
	struct sharp_memory_device *smd;
	struct drm_crtc_state *crtc_state;

	smd = container_of(plane, struct sharp_memory_device, plane);
	crtc_state = drm_atomic_get_new_crtc_state(state, &smd->crtc);

	return drm_atomic_helper_check_plane_state(plane_state, crtc_state,
						   DRM_PLANE_NO_SCALING,
						   DRM_PLANE_NO_SCALING,
						   false, false);
}

static void sharp_memory_plane_atomic_update(struct drm_plane *plane,
					     struct drm_atomic_state *state)
{
	struct drm_plane_state *old_state = drm_atomic_get_old_plane_state(state, plane);
	struct drm_plane_state *plane_state = plane->state;
	struct drm_format_conv_state fmtcnv_state = DRM_FORMAT_CONV_STATE_INIT;
	struct sharp_memory_device *smd;
	struct drm_rect rect;

	smd = container_of(plane, struct sharp_memory_device, plane);
	if (!smd->crtc.state->active)
		return;

	if (drm_atomic_helper_damage_merged(old_state, plane_state, &rect))
		sharp_memory_fb_dirty(plane_state->fb, &rect, &fmtcnv_state);

	drm_format_conv_state_release(&fmtcnv_state);
}

static const struct drm_plane_helper_funcs sharp_memory_plane_helper_funcs = {
	.prepare_fb = drm_gem_plane_helper_prepare_fb,
	.atomic_check = sharp_memory_plane_atomic_check,
	.atomic_update = sharp_memory_plane_atomic_update,
};

static bool sharp_memory_format_mod_supported(struct drm_plane *plane,
					      u32 format,
					      u64 modifier)
{
	return modifier == DRM_FORMAT_MOD_LINEAR;
}

static const struct drm_plane_funcs sharp_memory_plane_funcs = {
	.update_plane = drm_atomic_helper_update_plane,
	.disable_plane = drm_atomic_helper_disable_plane,
	.destroy = drm_plane_cleanup,
	.reset = drm_atomic_helper_plane_reset,
	.atomic_duplicate_state	= drm_atomic_helper_plane_duplicate_state,
	.atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
	.format_mod_supported = sharp_memory_format_mod_supported,
};

static enum drm_mode_status sharp_memory_crtc_mode_valid(struct drm_crtc *crtc,
							 const struct drm_display_mode *mode)
{
	struct sharp_memory_device *smd = drm_to_sharp_memory_device(crtc->dev);

	return drm_crtc_helper_mode_valid_fixed(crtc, mode, smd->mode);
}

static int sharp_memory_crtc_check(struct drm_crtc *crtc,
				   struct drm_atomic_state *state)
{
	struct drm_crtc_state *crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
	int ret;

	if (!crtc_state->enable)
		goto out;

	ret = drm_atomic_helper_check_crtc_primary_plane(crtc_state);
	if (ret)
		return ret;

out:
	return drm_atomic_add_affected_planes(state, crtc);
}

static int sharp_memory_sw_vcom_signal_thread(void *data)
{
	struct sharp_memory_device *smd = data;

	while (!kthread_should_stop()) {
		smd->vcom ^= 1; /* Toggle vcom */
		sharp_memory_maintain_display(smd);
		msleep(1000);
	}

	return 0;
}

static void sharp_memory_crtc_enable(struct drm_crtc *crtc,
				     struct drm_atomic_state *state)
{
	struct sharp_memory_device *smd = drm_to_sharp_memory_device(crtc->dev);

	sharp_memory_clear_display(smd);

	if (smd->enable_gpio)
		gpiod_set_value(smd->enable_gpio, 1);
}

static void sharp_memory_crtc_disable(struct drm_crtc *crtc,
				      struct drm_atomic_state *state)
{
	struct sharp_memory_device *smd = drm_to_sharp_memory_device(crtc->dev);

	sharp_memory_clear_display(smd);

	if (smd->enable_gpio)
		gpiod_set_value(smd->enable_gpio, 0);
}

static const struct drm_crtc_helper_funcs sharp_memory_crtc_helper_funcs = {
	.mode_valid = sharp_memory_crtc_mode_valid,
	.atomic_check = sharp_memory_crtc_check,
	.atomic_enable = sharp_memory_crtc_enable,
	.atomic_disable = sharp_memory_crtc_disable,
};

static const struct drm_crtc_funcs sharp_memory_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,
};

static const struct drm_encoder_funcs sharp_memory_encoder_funcs = {
	.destroy = drm_encoder_cleanup,
};

static int sharp_memory_connector_get_modes(struct drm_connector *connector)
{
	struct sharp_memory_device *smd = drm_to_sharp_memory_device(connector->dev);

	return drm_connector_helper_get_modes_fixed(connector, smd->mode);
}

static const struct drm_connector_helper_funcs sharp_memory_connector_hfuncs = {
	.get_modes = sharp_memory_connector_get_modes,
};

static const struct drm_connector_funcs sharp_memory_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 sharp_memory_mode_config_funcs = {
	.fb_create = drm_gem_fb_create_with_dirty,
	.atomic_check = drm_atomic_helper_check,
	.atomic_commit = drm_atomic_helper_commit,
};

static const struct drm_display_mode sharp_memory_ls010b7dh04_mode = {
	DRM_SIMPLE_MODE(128, 128, 18, 18),
};

static const struct drm_display_mode sharp_memory_ls011b7dh03_mode = {
	DRM_SIMPLE_MODE(160, 68, 25, 10),
};

static const struct drm_display_mode sharp_memory_ls012b7dd01_mode = {
	DRM_SIMPLE_MODE(184, 38, 29, 6),
};

static const struct drm_display_mode sharp_memory_ls013b7dh03_mode = {
	DRM_SIMPLE_MODE(128, 128, 23, 23),
};

static const struct drm_display_mode sharp_memory_ls013b7dh05_mode = {
	DRM_SIMPLE_MODE(144, 168, 20, 24),
};

static const struct drm_display_mode sharp_memory_ls018b7dh02_mode = {
	DRM_SIMPLE_MODE(230, 303, 27, 36),
};

static const struct drm_display_mode sharp_memory_ls027b7dh01_mode = {
	DRM_SIMPLE_MODE(400, 240, 58, 35),
};

static const struct drm_display_mode sharp_memory_ls032b7dd02_mode = {
	DRM_SIMPLE_MODE(336, 536, 42, 68),
};

static const struct drm_display_mode sharp_memory_ls044q7dh01_mode = {
	DRM_SIMPLE_MODE(320, 240, 89, 67),
};

static const struct spi_device_id sharp_memory_ids[] = {
	{"ls010b7dh04", (kernel_ulong_t)&sharp_memory_ls010b7dh04_mode},
	{"ls011b7dh03", (kernel_ulong_t)&sharp_memory_ls011b7dh03_mode},
	{"ls012b7dd01", (kernel_ulong_t)&sharp_memory_ls012b7dd01_mode},
	{"ls013b7dh03", (kernel_ulong_t)&sharp_memory_ls013b7dh03_mode},
	{"ls013b7dh05", (kernel_ulong_t)&sharp_memory_ls013b7dh05_mode},
	{"ls018b7dh02", (kernel_ulong_t)&sharp_memory_ls018b7dh02_mode},
	{"ls027b7dh01", (kernel_ulong_t)&sharp_memory_ls027b7dh01_mode},
	{"ls027b7dh01a", (kernel_ulong_t)&sharp_memory_ls027b7dh01_mode},
	{"ls032b7dd02", (kernel_ulong_t)&sharp_memory_ls032b7dd02_mode},
	{"ls044q7dh01", (kernel_ulong_t)&sharp_memory_ls044q7dh01_mode},
	{},
};
MODULE_DEVICE_TABLE(spi, sharp_memory_ids);

static const struct of_device_id sharp_memory_of_match[] = {
	{.compatible = "sharp,ls010b7dh04", &sharp_memory_ls010b7dh04_mode},
	{.compatible = "sharp,ls011b7dh03", &sharp_memory_ls011b7dh03_mode},
	{.compatible = "sharp,ls012b7dd01", &sharp_memory_ls012b7dd01_mode},
	{.compatible = "sharp,ls013b7dh03", &sharp_memory_ls013b7dh03_mode},
	{.compatible = "sharp,ls013b7dh05", &sharp_memory_ls013b7dh05_mode},
	{.compatible = "sharp,ls018b7dh02", &sharp_memory_ls018b7dh02_mode},
	{.compatible = "sharp,ls027b7dh01", &sharp_memory_ls027b7dh01_mode},
	{.compatible = "sharp,ls027b7dh01a", &sharp_memory_ls027b7dh01_mode},
	{.compatible = "sharp,ls032b7dd02", &sharp_memory_ls032b7dd02_mode},
	{.compatible = "sharp,ls044q7dh01", &sharp_memory_ls044q7dh01_mode},
	{},
};
MODULE_DEVICE_TABLE(of, sharp_memory_of_match);

static const u32 sharp_memory_formats[] = {
	DRM_FORMAT_XRGB8888,
};

static int sharp_memory_pipe_init(struct drm_device *dev,
				  struct sharp_memory_device *smd,
				  const u32 *formats, unsigned int format_count,
				  const u64 *format_modifiers)
{
	int ret;
	struct drm_encoder *encoder = &smd->encoder;
	struct drm_plane *plane = &smd->plane;
	struct drm_crtc *crtc = &smd->crtc;
	struct drm_connector *connector = &smd->connector;

	drm_plane_helper_add(plane, &sharp_memory_plane_helper_funcs);
	ret = drm_universal_plane_init(dev, plane, 0,
				       &sharp_memory_plane_funcs,
				       formats, format_count,
				       format_modifiers,
				       DRM_PLANE_TYPE_PRIMARY, NULL);
	if (ret)
		return ret;

	drm_crtc_helper_add(crtc, &sharp_memory_crtc_helper_funcs);
	ret = drm_crtc_init_with_planes(dev, crtc, plane, NULL,
					&sharp_memory_crtc_funcs, NULL);
	if (ret)
		return ret;

	encoder->possible_crtcs = drm_crtc_mask(crtc);
	ret = drm_encoder_init(dev, encoder, &sharp_memory_encoder_funcs,
			       DRM_MODE_ENCODER_NONE, NULL);
	if (ret)
		return ret;

	ret = drm_connector_init(&smd->drm, &smd->connector,
				 &sharp_memory_connector_funcs,
				 DRM_MODE_CONNECTOR_SPI);
	if (ret)
		return ret;

	drm_connector_helper_add(&smd->connector,
				 &sharp_memory_connector_hfuncs);

	return drm_connector_attach_encoder(connector, encoder);
}

static int sharp_memory_init_pwm_vcom_signal(struct sharp_memory_device *smd)
{
	int ret;
	struct device *dev = &smd->spi->dev;
	struct pwm_state pwm_state;

	smd->pwm_vcom_signal = devm_pwm_get(dev, NULL);
	if (IS_ERR(smd->pwm_vcom_signal))
		return dev_err_probe(dev, PTR_ERR(smd->pwm_vcom_signal),
				     "Could not get pwm device\n");

	pwm_init_state(smd->pwm_vcom_signal, &pwm_state);
	pwm_set_relative_duty_cycle(&pwm_state, 1, 10);
	pwm_state.enabled = true;
	ret = pwm_apply_might_sleep(smd->pwm_vcom_signal, &pwm_state);
	if (ret)
		return dev_err_probe(dev, -EINVAL, "Could not apply pwm state\n");

	return 0;
}

static int sharp_memory_probe(struct spi_device *spi)
{
	int ret;
	struct device *dev;
	struct sharp_memory_device *smd;
	struct drm_device *drm;
	const char *vcom_mode_str;

	dev = &spi->dev;

	ret = spi_setup(spi);
	if (ret < 0)
		return dev_err_probe(dev, ret, "Failed to setup spi device\n");

	if (!dev->coherent_dma_mask) {
		ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
		if (ret)
			return dev_err_probe(dev, ret, "Failed to set dma mask\n");
	}

	smd = devm_drm_dev_alloc(dev, &sharp_memory_drm_driver,
				 struct sharp_memory_device, drm);
	if (!smd)
		return -ENOMEM;

	spi_set_drvdata(spi, smd);

	smd->spi = spi;
	drm = &smd->drm;
	ret = drmm_mode_config_init(drm);
	if (ret)
		return dev_err_probe(dev, ret, "Failed to initialize drm config\n");

	smd->enable_gpio = devm_gpiod_get_optional(dev, "enable", GPIOD_OUT_HIGH);
	if (!smd->enable_gpio)
		dev_warn(dev, "Enable gpio not defined\n");

	drm->mode_config.funcs = &sharp_memory_mode_config_funcs;
	smd->mode = spi_get_device_match_data(spi);

	smd->pitch = (SHARP_ADDR_PERIOD + smd->mode->hdisplay + SHARP_DUMMY_PERIOD) / 8;
	smd->tx_buffer_size = (SHARP_MODE_PERIOD +
			       (SHARP_ADDR_PERIOD + (smd->mode->hdisplay) + SHARP_DUMMY_PERIOD) *
			       smd->mode->vdisplay) / 8;

	smd->tx_buffer = devm_kzalloc(dev, smd->tx_buffer_size, GFP_KERNEL);
	if (!smd->tx_buffer)
		return -ENOMEM;

	mutex_init(&smd->tx_mutex);

	/*
	 * VCOM is a signal that prevents DC bias from being built up in
	 * the panel resulting in pixels being forever stuck in one state.
	 *
	 * This driver supports three different methods to generate this
	 * signal depending on EXTMODE pin:
	 *
	 * software (EXTMODE = L) - This mode uses a kthread to
	 * periodically send a "maintain display" message to the display,
	 * toggling the vcom bit on and off with each message
	 *
	 * external (EXTMODE = H) - This mode relies on an external
	 * clock to generate the signal on the EXTCOMM pin
	 *
	 * pwm (EXTMODE = H) - This mode uses a pwm device to generate
	 * the signal on the EXTCOMM pin
	 *
	 */
	if (device_property_read_string(dev, "sharp,vcom-mode", &vcom_mode_str))
		return dev_err_probe(dev, -EINVAL,
				     "Unable to find sharp,vcom-mode node in device tree\n");

	if (!strcmp("software", vcom_mode_str)) {
		smd->vcom_mode = SHARP_MEMORY_SOFTWARE_VCOM;
		smd->sw_vcom_signal = kthread_run(sharp_memory_sw_vcom_signal_thread,
						  smd, "sw_vcom_signal");

	} else if (!strcmp("external", vcom_mode_str)) {
		smd->vcom_mode = SHARP_MEMORY_EXTERNAL_VCOM;

	} else if (!strcmp("pwm", vcom_mode_str)) {
		smd->vcom_mode = SHARP_MEMORY_PWM_VCOM;
		ret = sharp_memory_init_pwm_vcom_signal(smd);
		if (ret)
			return ret;
	} else {
		return dev_err_probe(dev, -EINVAL, "Invalid value set for vcom-mode\n");
	}

	drm->mode_config.min_width = smd->mode->hdisplay;
	drm->mode_config.max_width = smd->mode->hdisplay;
	drm->mode_config.min_height = smd->mode->vdisplay;
	drm->mode_config.max_height = smd->mode->vdisplay;

	ret = sharp_memory_pipe_init(drm, smd, sharp_memory_formats,
				     ARRAY_SIZE(sharp_memory_formats),
				     NULL);
	if (ret)
		return dev_err_probe(dev, ret, "Failed to initialize display pipeline.\n");

	drm_plane_enable_fb_damage_clips(&smd->plane);
	drm_mode_config_reset(drm);

	ret = drm_dev_register(drm, 0);
	if (ret)
		return dev_err_probe(dev, ret, "Failed to register drm device.\n");

	drm_client_setup(drm, NULL);

	return 0;
}

static void sharp_memory_remove(struct spi_device *spi)
{
	struct sharp_memory_device *smd = spi_get_drvdata(spi);

	drm_dev_unplug(&smd->drm);
	drm_atomic_helper_shutdown(&smd->drm);

	switch (smd->vcom_mode) {
	case SHARP_MEMORY_SOFTWARE_VCOM:
		kthread_stop(smd->sw_vcom_signal);
		break;

	case SHARP_MEMORY_EXTERNAL_VCOM:
		break;

	case SHARP_MEMORY_PWM_VCOM:
		pwm_disable(smd->pwm_vcom_signal);
		break;
	}
}

static struct spi_driver sharp_memory_spi_driver = {
	.driver = {
		.name = "sharp_memory",
		.of_match_table = sharp_memory_of_match,
	},
	.probe = sharp_memory_probe,
	.remove = sharp_memory_remove,
	.id_table = sharp_memory_ids,
};
module_spi_driver(sharp_memory_spi_driver);

MODULE_AUTHOR("Alex Lanzano <lanzano.alex@gmail.com>");
MODULE_DESCRIPTION("SPI Protocol driver for the sharp_memory display");
MODULE_LICENSE("GPL");