[RFC PATCH] drivers: Raspbery Pi Sense Hat

[Joel Savitz <jsavitz@redhat.com>]

From: Joel Savitz <joelsavitz@gmail.com>

This is a forward port of the Rapsberry Pi Sense Hat driver from the
downstream Raspberry Pi kernel tree.

I have slightly consolidated things and done some quick testing of this
driver on Fedora (which comes with the device tree blobs), and I want to
do a bit more testing before submiting the driver for inclusion in
mainline Linux.

I would like to get some feedback from the community on what may need to
be improved, fixed, or changed as early as possible, so this is a request
for comments.

Signed-off-by: Joel Savitz <joelsavitz@gmail.com>
---
 drivers/input/joystick/Kconfig       |   8 +
 drivers/input/joystick/Makefile      |   1 +
 drivers/input/joystick/rpisense-js.c | 147 ++++++++++++++
 drivers/mfd/Kconfig                  |   8 +
 drivers/mfd/Makefile                 |   1 +
 drivers/mfd/rpisense-core.c          | 162 +++++++++++++++
 drivers/video/fbdev/Kconfig          |  13 ++
 drivers/video/fbdev/Makefile         |   1 +
 drivers/video/fbdev/rpisense-fb.c    | 291 +++++++++++++++++++++++++++
 include/linux/mfd/rpisense.h         |  66 ++++++
 10 files changed, 698 insertions(+)
 create mode 100644 drivers/input/joystick/rpisense-js.c
 create mode 100644 drivers/mfd/rpisense-core.c
 create mode 100644 drivers/video/fbdev/rpisense-fb.c
 create mode 100644 include/linux/mfd/rpisense.h

diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
index 5e38899058c1..1c0025c22bf4 100644
--- a/drivers/input/joystick/Kconfig
+++ b/drivers/input/joystick/Kconfig
@@ -389,4 +389,12 @@ config JOYSTICK_N64
 	  Say Y here if you want enable support for the four
 	  built-in controller ports on the Nintendo 64 console.
 
+config JOYSTICK_RPISENSE
+	tristate "Raspberry Pi Sense HAT joystick"
+	depends on GPIOLIB && INPUT
+	select MFD_RPISENSE_CORE
+
+	help
+	  This is the joystick driver for the Raspberry Pi Sense HAT
+
 endif
diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
index 31d720c9e493..b227e98cd179 100644
--- a/drivers/input/joystick/Makefile
+++ b/drivers/input/joystick/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_JOYSTICK_MAPLE)		+= maplecontrol.o
 obj-$(CONFIG_JOYSTICK_N64)		+= n64joy.o
 obj-$(CONFIG_JOYSTICK_PSXPAD_SPI)	+= psxpad-spi.o
 obj-$(CONFIG_JOYSTICK_PXRC)		+= pxrc.o
+obj-$(CONFIG_JOYSTICK_RPISENSE)         += rpisense-js.o
 obj-$(CONFIG_JOYSTICK_SIDEWINDER)	+= sidewinder.o
 obj-$(CONFIG_JOYSTICK_SPACEBALL)	+= spaceball.o
 obj-$(CONFIG_JOYSTICK_SPACEORB)		+= spaceorb.o
diff --git a/drivers/input/joystick/rpisense-js.c b/drivers/input/joystick/rpisense-js.c
new file mode 100644
index 000000000000..41d4bd1fed46
--- /dev/null
+++ b/drivers/input/joystick/rpisense-js.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Raspberry Pi Sense HAT joystick driver
+ * http://raspberrypi.org
+ *
+ * Copyright (C) 2015 Raspberry Pi
+ *
+ * Author: Serge Schneider
+ * Adapted for mainline Linux by: Joel Savitz
+ */
+
+#include <linux/module.h>
+#include <linux/mfd/rpisense.h>
+
+static struct rpisense *rpisense;
+static unsigned char keymap[5] = {KEY_DOWN, KEY_RIGHT, KEY_UP, KEY_ENTER, KEY_LEFT,};
+
+static void keys_work_fn(struct work_struct *work)
+{
+	int i;
+	static s32 prev_keys;
+	struct rpisense_js *rpisense_js = &rpisense->joystick;
+	s32 keys = rpisense_reg_read(rpisense, RPISENSE_KEYS);
+	s32 changes = keys ^ prev_keys;
+
+	prev_keys = keys;
+	for (i = 0; i < 5; i++) {
+		if (changes & 1) {
+			input_report_key(rpisense_js->keys_dev,
+					 keymap[i], keys & 1);
+		}
+		changes >>= 1;
+		keys >>= 1;
+	}
+	input_sync(rpisense_js->keys_dev);
+}
+
+static irqreturn_t keys_irq_handler(int irq, void *pdev)
+{
+	struct rpisense_js *rpisense_js = &rpisense->joystick;
+
+	schedule_work(&rpisense_js->keys_work_s);
+	return IRQ_HANDLED;
+}
+
+static int rpisense_js_probe(struct platform_device *pdev)
+{
+	int ret;
+	int i;
+	struct rpisense_js *rpisense_js;
+
+	rpisense = rpisense_get_dev();
+	rpisense_js = &rpisense->joystick;
+
+	INIT_WORK(&rpisense_js->keys_work_s, keys_work_fn);
+
+	rpisense_js->keys_dev = input_allocate_device();
+	if (!rpisense_js->keys_dev) {
+		dev_err(&pdev->dev, "Could not allocate input device.\n");
+		return -ENOMEM;
+	}
+
+	rpisense_js->keys_dev->evbit[0] = BIT_MASK(EV_KEY);
+	for (i = 0; i < ARRAY_SIZE(keymap); i++) {
+		set_bit(keymap[i],
+			rpisense_js->keys_dev->keybit);
+	}
+
+	rpisense_js->keys_dev->name = "Raspberry Pi Sense HAT Joystick";
+	rpisense_js->keys_dev->phys = "rpi-sense-joy/input0";
+	rpisense_js->keys_dev->id.bustype = BUS_I2C;
+	rpisense_js->keys_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
+	rpisense_js->keys_dev->keycode = keymap;
+	rpisense_js->keys_dev->keycodesize = sizeof(unsigned char);
+	rpisense_js->keys_dev->keycodemax = ARRAY_SIZE(keymap);
+
+	ret = input_register_device(rpisense_js->keys_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not register input device.\n");
+		goto err_keys_alloc;
+	}
+
+	ret = gpiod_direction_input(rpisense_js->keys_desc);
+	if (ret) {
+		dev_err(&pdev->dev, "Could not set keys-int direction.\n");
+		goto err_keys_reg;
+	}
+
+	rpisense_js->keys_irq = gpiod_to_irq(rpisense_js->keys_desc);
+	if (rpisense_js->keys_irq < 0) {
+		dev_err(&pdev->dev, "Could not determine keys-int IRQ.\n");
+		ret = rpisense_js->keys_irq;
+		goto err_keys_reg;
+	}
+
+	ret = devm_request_irq(&pdev->dev, rpisense_js->keys_irq,
+			       keys_irq_handler, IRQF_TRIGGER_RISING,
+			       "keys", &pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "IRQ request failed.\n");
+		goto err_keys_reg;
+	}
+	return 0;
+err_keys_reg:
+	input_unregister_device(rpisense_js->keys_dev);
+err_keys_alloc:
+	input_free_device(rpisense_js->keys_dev);
+	return ret;
+}
+
+static int rpisense_js_remove(struct platform_device *pdev)
+{
+	struct rpisense_js *rpisense_js = &rpisense->joystick;
+
+	input_unregister_device(rpisense_js->keys_dev);
+	input_free_device(rpisense_js->keys_dev);
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id rpisense_js_id[] = {
+	{ .compatible = "raspberrypi,rpi-sense-js" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, rpisense_js_id);
+#endif
+
+static struct platform_device_id rpisense_js_device_id[] = {
+	{ .name = "rpi-sense-js" },
+	{ },
+};
+MODULE_DEVICE_TABLE(platform, rpisense_js_device_id);
+
+static struct platform_driver rpisense_js_driver = {
+	.probe = rpisense_js_probe,
+	.remove = rpisense_js_remove,
+	.driver = {
+		.name = "rpi-sense-js",
+		.owner = THIS_MODULE,
+	},
+};
+
+module_platform_driver(rpisense_js_driver);
+
+MODULE_DESCRIPTION("Raspberry Pi Sense HAT joystick driver");
+MODULE_AUTHOR("Serge Schneider <serge@raspberrypi.org>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index b74efa469e90..8c309e389359 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -11,6 +11,14 @@ config MFD_CORE
 	select IRQ_DOMAIN
 	default n
 
+config MFD_RPISENSE_CORE
+	tristate "Raspberry Pi Sense HAT core functions"
+	depends on I2C
+	select MFD_CORE
+	help
+	  This is the core driver for the Raspberry Pi Sense HAT. This provides
+	  the necessary functions to communicate with the hardware.
+
 config MFD_CS5535
 	tristate "AMD CS5535 and CS5536 southbridge core functions"
 	select MFD_CORE
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 834f5463af28..7140a8fc36ee 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -263,6 +263,7 @@ obj-$(CONFIG_MFD_ROHM_BD71828)	+= rohm-bd71828.o
 obj-$(CONFIG_MFD_ROHM_BD718XX)	+= rohm-bd718x7.o
 obj-$(CONFIG_MFD_STMFX) 	+= stmfx.o
 obj-$(CONFIG_MFD_KHADAS_MCU) 	+= khadas-mcu.o
+obj-$(CONFIG_MFD_RPISENSE_CORE) += rpisense-core.o
 obj-$(CONFIG_MFD_ACER_A500_EC)	+= acer-ec-a500.o
 
 obj-$(CONFIG_SGI_MFD_IOC3)	+= ioc3.o
diff --git a/drivers/mfd/rpisense-core.c b/drivers/mfd/rpisense-core.c
new file mode 100644
index 000000000000..aa2c394c5e67
--- /dev/null
+++ b/drivers/mfd/rpisense-core.c
@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Raspberry Pi Sense HAT core driver
+ * http://raspberrypi.org
+ *
+ * Copyright (C) 2015 Raspberry Pi
+ *
+ * Author: Serge Schneider
+ * Adapted for mainline Linux by: Joel Savitz
+ *
+ *  This driver is based on wm8350 implementation.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+
+#include <linux/mfd/rpisense.h>
+
+static struct rpisense *rpisense;
+
+static void rpisense_client_dev_register(struct rpisense *rpisense,
+					 const char *name,
+					 struct platform_device **pdev)
+{
+	int ret;
+
+	*pdev = platform_device_alloc(name, -1);
+	if (*pdev == NULL) {
+		dev_err(rpisense->dev, "Failed to allocate %s\n", name);
+		return;
+	}
+
+	(*pdev)->dev.parent = rpisense->dev;
+	platform_set_drvdata(*pdev, rpisense);
+	ret = platform_device_add(*pdev);
+	if (ret != 0) {
+		dev_err(rpisense->dev, "Failed to register %s: %d\n",
+			name, ret);
+		platform_device_put(*pdev);
+		*pdev = NULL;
+	}
+}
+
+static int rpisense_probe(struct i2c_client *i2c,
+			       const struct i2c_device_id *id)
+{
+	int ret;
+	struct rpisense_js *rpisense_js;
+
+	rpisense = devm_kzalloc(&i2c->dev, sizeof(struct rpisense), GFP_KERNEL);
+	if (rpisense == NULL)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, rpisense);
+	rpisense->dev = &i2c->dev;
+	rpisense->i2c_client = i2c;
+
+	ret = rpisense_reg_read(rpisense, RPISENSE_WAI);
+	if (ret > 0) {
+		if (ret != 's')
+			return -EINVAL;
+	} else {
+		return ret;
+	}
+	ret = rpisense_reg_read(rpisense, RPISENSE_VER);
+	if (ret < 0)
+		return ret;
+
+	dev_info(rpisense->dev,
+		 "Raspberry Pi Sense HAT firmware version %i\n", ret);
+
+	rpisense_js = &rpisense->joystick;
+	rpisense_js->keys_desc = devm_gpiod_get(&i2c->dev,
+						"keys-int", GPIOD_IN);
+	if (IS_ERR(rpisense_js->keys_desc)) {
+		dev_warn(&i2c->dev, "Failed to get keys-int descriptor.\n");
+		rpisense_js->keys_desc = gpio_to_desc(23);
+		if (rpisense_js->keys_desc == NULL) {
+			dev_err(&i2c->dev, "GPIO23 fallback failed.\n");
+			return PTR_ERR(rpisense_js->keys_desc);
+		}
+	}
+	rpisense_client_dev_register(rpisense, "rpi-sense-js",
+				     &(rpisense->joystick.pdev));
+	rpisense_client_dev_register(rpisense, "rpi-sense-fb",
+				     &(rpisense->framebuffer.pdev));
+
+	return 0;
+}
+
+static int rpisense_remove(struct i2c_client *i2c)
+{
+	struct rpisense *rpisense = i2c_get_clientdata(i2c);
+
+	platform_device_unregister(rpisense->joystick.pdev);
+	return 0;
+}
+
+struct rpisense *rpisense_get_dev(void)
+{
+	return rpisense;
+}
+EXPORT_SYMBOL_GPL(rpisense_get_dev);
+
+s32 rpisense_reg_read(struct rpisense *rpisense, int reg)
+{
+	int ret = i2c_smbus_read_byte_data(rpisense->i2c_client, reg);
+
+	if (ret < 0)
+		dev_err(rpisense->dev, "Read from reg %d failed\n", reg);
+	/* Due to the BCM270x I2C clock stretching bug, some values
+	 * may have MSB set. Clear it to avoid incorrect values.
+	 */
+	return ret & 0x7F;
+}
+EXPORT_SYMBOL_GPL(rpisense_reg_read);
+
+int rpisense_block_write(struct rpisense *rpisense, const char *buf, int count)
+{
+	int ret = i2c_master_send(rpisense->i2c_client, buf, count);
+
+	if (ret < 0)
+		dev_err(rpisense->dev, "Block write failed\n");
+	return ret;
+}
+EXPORT_SYMBOL_GPL(rpisense_block_write);
+
+static const struct i2c_device_id rpisense_i2c_id[] = {
+	{ "rpi-sense", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, rpisense_i2c_id);
+
+#ifdef CONFIG_OF
+static const struct of_device_id rpisense_core_id[] = {
+	{ .compatible = "raspberrypi,rpi-sense" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, rpisense_core_id);
+#endif
+
+
+static struct i2c_driver rpisense_driver = {
+	.driver = {
+		   .name = "rpi-sense",
+		   .owner = THIS_MODULE,
+	},
+	.probe = rpisense_probe,
+	.remove = rpisense_remove,
+	.id_table = rpisense_i2c_id,
+};
+
+module_i2c_driver(rpisense_driver);
+
+MODULE_DESCRIPTION("Raspberry Pi Sense HAT core driver");
+MODULE_AUTHOR("Serge Schneider <serge@raspberrypi.org>");
+MODULE_LICENSE("GPL");
+
diff --git a/drivers/video/fbdev/Kconfig b/drivers/video/fbdev/Kconfig
index 4f02db65dede..2238e36e71e4 100644
--- a/drivers/video/fbdev/Kconfig
+++ b/drivers/video/fbdev/Kconfig
@@ -2236,6 +2236,19 @@ config FB_SM712
 	  called sm712fb. If you want to compile it as a module, say M
 	  here and read <file:Documentation/kbuild/modules.rst>.
 
+config FB_RPISENSE
+        tristate "Raspberry Pi Sense HAT framebuffer"
+        depends on FB
+        select MFD_RPISENSE_CORE
+        select FB_SYS_FOPS
+        select FB_SYS_FILLRECT
+        select FB_SYS_COPYAREA
+        select FB_SYS_IMAGEBLIT
+        select FB_DEFERRED_IO
+
+        help
+          This is the framebuffer driver for the Raspberry Pi Sense HAT
+
 source "drivers/video/fbdev/omap/Kconfig"
 source "drivers/video/fbdev/omap2/Kconfig"
 source "drivers/video/fbdev/mmp/Kconfig"
diff --git a/drivers/video/fbdev/Makefile b/drivers/video/fbdev/Makefile
index 477b9624b703..5b17203b7e43 100644
--- a/drivers/video/fbdev/Makefile
+++ b/drivers/video/fbdev/Makefile
@@ -129,6 +129,7 @@ obj-$(CONFIG_FB_MX3)		  += mx3fb.o
 obj-$(CONFIG_FB_DA8XX)		  += da8xx-fb.o
 obj-$(CONFIG_FB_SSD1307)	  += ssd1307fb.o
 obj-$(CONFIG_FB_SIMPLE)           += simplefb.o
+obj-$(CONFIG_FB_RPISENSE)         += rpisense-fb.o
 
 # the test framebuffer is last
 obj-$(CONFIG_FB_VIRTUAL)          += vfb.o
diff --git a/drivers/video/fbdev/rpisense-fb.c b/drivers/video/fbdev/rpisense-fb.c
new file mode 100644
index 000000000000..a90a5ec51fd7
--- /dev/null
+++ b/drivers/video/fbdev/rpisense-fb.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Raspberry Pi Sense HAT framebuffer driver
+ * http://raspberrypi.org
+ *
+ * Copyright (C) 2015 Raspberry Pi
+ *
+ * Author: Serge Schneider
+ * Adapted for mainline Linux by: Joel Savitz
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/delay.h>
+#include <linux/fb.h>
+#include <linux/init.h>
+
+#include <linux/mfd/rpisense.h>
+
+static bool lowlight;
+module_param(lowlight, bool, 0);
+MODULE_PARM_DESC(lowlight, "Reduce LED matrix brightness to one third");
+
+static struct rpisense *rpisense;
+
+struct rpisense_fb_param {
+	char __iomem *vmem;
+	u8 *vmem_work;
+	u32 vmemsize;
+	u8 *gamma;
+};
+
+static u8 gamma_default[32] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01,
+			       0x02, 0x02, 0x03, 0x03, 0x04, 0x05, 0x06, 0x07,
+			       0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0E, 0x0F, 0x11,
+			       0x12, 0x14, 0x15, 0x17, 0x19, 0x1B, 0x1D, 0x1F,};
+
+static u8 gamma_low[32] = {0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01,
+			   0x01, 0x01, 0x01, 0x01, 0x01, 0x02, 0x02, 0x02,
+			   0x03, 0x03, 0x03, 0x04, 0x04, 0x05, 0x05, 0x06,
+			   0x06, 0x07, 0x07, 0x08, 0x08, 0x09, 0x0A, 0x0A,};
+
+static u8 gamma_user[32];
+
+static u32 pseudo_palette[16];
+
+static struct rpisense_fb_param rpisense_fb_param = {
+	.vmem = NULL,
+	.vmemsize = 128,
+	.gamma = gamma_default,
+};
+
+static struct fb_deferred_io rpisense_fb_defio;
+
+static struct fb_fix_screeninfo rpisense_fb_fix = {
+	.id =		"RPi-Sense FB",
+	.type =		FB_TYPE_PACKED_PIXELS,
+	.visual =	FB_VISUAL_TRUECOLOR,
+	.xpanstep =	0,
+	.ypanstep =	0,
+	.ywrapstep =	0,
+	.accel =	FB_ACCEL_NONE,
+	.line_length =	16,
+};
+
+static struct fb_var_screeninfo rpisense_fb_var = {
+	.xres		= 8,
+	.yres		= 8,
+	.xres_virtual	= 8,
+	.yres_virtual	= 8,
+	.bits_per_pixel = 16,
+	.red		= {11, 5, 0},
+	.green		= {5, 6, 0},
+	.blue		= {0, 5, 0},
+};
+
+static ssize_t rpisense_fb_write(struct fb_info *info,
+				 const char __user *buf, size_t count,
+				 loff_t *ppos)
+{
+	ssize_t res = fb_sys_write(info, buf, count, ppos);
+
+	schedule_delayed_work(&info->deferred_work, rpisense_fb_defio.delay);
+	return res;
+}
+
+static void rpisense_fb_fillrect(struct fb_info *info,
+				 const struct fb_fillrect *rect)
+{
+	sys_fillrect(info, rect);
+	schedule_delayed_work(&info->deferred_work, rpisense_fb_defio.delay);
+}
+
+static void rpisense_fb_copyarea(struct fb_info *info,
+				 const struct fb_copyarea *area)
+{
+	sys_copyarea(info, area);
+	schedule_delayed_work(&info->deferred_work, rpisense_fb_defio.delay);
+}
+
+static void rpisense_fb_imageblit(struct fb_info *info,
+				  const struct fb_image *image)
+{
+	sys_imageblit(info, image);
+	schedule_delayed_work(&info->deferred_work, rpisense_fb_defio.delay);
+}
+
+static void rpisense_fb_deferred_io(struct fb_info *info,
+				struct list_head *pagelist)
+{
+	int i;
+	int j;
+	u8 *vmem_work = rpisense_fb_param.vmem_work;
+	u16 *mem = (u16 *)rpisense_fb_param.vmem;
+	u8 *gamma = rpisense_fb_param.gamma;
+
+	vmem_work[0] = 0;
+	for (j = 0; j < 8; j++) {
+		for (i = 0; i < 8; i++) {
+			vmem_work[(j * 24) + i + 1] =
+				gamma[(mem[(j * 8) + i] >> 11) & 0x1F];
+			vmem_work[(j * 24) + (i + 8) + 1] =
+				gamma[(mem[(j * 8) + i] >> 6) & 0x1F];
+			vmem_work[(j * 24) + (i + 16) + 1] =
+				gamma[(mem[(j * 8) + i]) & 0x1F];
+		}
+	}
+	rpisense_block_write(rpisense, vmem_work, 193);
+}
+
+static struct fb_deferred_io rpisense_fb_defio = {
+	.delay		= HZ/100,
+	.deferred_io	= rpisense_fb_deferred_io,
+};
+
+static int rpisense_fb_ioctl(struct fb_info *info, unsigned int cmd,
+			     unsigned long arg)
+{
+	switch (cmd) {
+	case SENSEFB_FBIOGET_GAMMA:
+		if (copy_to_user((void __user *) arg, rpisense_fb_param.gamma,
+				 sizeof(u8[32])))
+			return -EFAULT;
+		return 0;
+	case SENSEFB_FBIOSET_GAMMA:
+		if (copy_from_user(gamma_user, (void __user *)arg,
+				   sizeof(u8[32])))
+			return -EFAULT;
+		rpisense_fb_param.gamma = gamma_user;
+		schedule_delayed_work(&info->deferred_work,
+				      rpisense_fb_defio.delay);
+		return 0;
+	case SENSEFB_FBIORESET_GAMMA:
+		switch (arg) {
+		case 0:
+			rpisense_fb_param.gamma = gamma_default;
+			break;
+		case 1:
+			rpisense_fb_param.gamma = gamma_low;
+			break;
+		case 2:
+			rpisense_fb_param.gamma = gamma_user;
+			break;
+		default:
+			return -EINVAL;
+		}
+		schedule_delayed_work(&info->deferred_work,
+				      rpisense_fb_defio.delay);
+		break;
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static struct fb_ops rpisense_fb_ops = {
+	.owner		= THIS_MODULE,
+	.fb_read	= fb_sys_read,
+	.fb_write	= rpisense_fb_write,
+	.fb_fillrect	= rpisense_fb_fillrect,
+	.fb_copyarea	= rpisense_fb_copyarea,
+	.fb_imageblit	= rpisense_fb_imageblit,
+	.fb_ioctl	= rpisense_fb_ioctl,
+};
+
+static int rpisense_fb_probe(struct platform_device *pdev)
+{
+	struct fb_info *info;
+	int ret = -ENOMEM;
+	struct rpisense_fb *rpisense_fb;
+
+	rpisense = rpisense_get_dev();
+	rpisense_fb = &rpisense->framebuffer;
+
+	rpisense_fb_param.vmem = vzalloc(rpisense_fb_param.vmemsize);
+	if (!rpisense_fb_param.vmem)
+		return ret;
+
+	rpisense_fb_param.vmem_work = devm_kmalloc(&pdev->dev, 193, GFP_KERNEL);
+	if (!rpisense_fb_param.vmem_work)
+		goto err_malloc;
+
+	info = framebuffer_alloc(0, &pdev->dev);
+	if (!info) {
+		dev_err(&pdev->dev, "Could not allocate framebuffer.\n");
+		goto err_malloc;
+	}
+	rpisense_fb->info = info;
+
+	rpisense_fb_fix.smem_start = (unsigned long)rpisense_fb_param.vmem;
+	rpisense_fb_fix.smem_len = rpisense_fb_param.vmemsize;
+
+	info->fbops = &rpisense_fb_ops;
+	info->fix = rpisense_fb_fix;
+	info->var = rpisense_fb_var;
+	info->fbdefio = &rpisense_fb_defio;
+	info->flags = FBINFO_FLAG_DEFAULT | FBINFO_VIRTFB;
+	info->screen_base = rpisense_fb_param.vmem;
+	info->screen_size = rpisense_fb_param.vmemsize;
+	info->pseudo_palette = pseudo_palette;
+
+	if (lowlight)
+		rpisense_fb_param.gamma = gamma_low;
+
+	fb_deferred_io_init(info);
+
+	ret = register_framebuffer(info);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Could not register framebuffer.\n");
+		goto err_fballoc;
+	}
+
+	fb_info(info, "%s frame buffer device\n", info->fix.id);
+	schedule_delayed_work(&info->deferred_work, rpisense_fb_defio.delay);
+	return 0;
+err_fballoc:
+	framebuffer_release(info);
+err_malloc:
+	vfree(rpisense_fb_param.vmem);
+	return ret;
+}
+
+static int rpisense_fb_remove(struct platform_device *pdev)
+{
+	struct rpisense_fb *rpisense_fb = &rpisense->framebuffer;
+	struct fb_info *info = rpisense_fb->info;
+
+	if (info) {
+		unregister_framebuffer(info);
+		fb_deferred_io_cleanup(info);
+		framebuffer_release(info);
+		vfree(rpisense_fb_param.vmem);
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id rpisense_fb_id[] = {
+	{ .compatible = "raspberrypi,rpi-sense-fb" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, rpisense_fb_id);
+#endif
+
+static struct platform_device_id rpisense_fb_device_id[] = {
+	{ .name = "rpi-sense-fb" },
+	{ },
+};
+MODULE_DEVICE_TABLE(platform, rpisense_fb_device_id);
+
+static struct platform_driver rpisense_fb_driver = {
+	.probe = rpisense_fb_probe,
+	.remove = rpisense_fb_remove,
+	.driver = {
+		.name = "rpi-sense-fb",
+		.owner = THIS_MODULE,
+	},
+};
+
+module_platform_driver(rpisense_fb_driver);
+
+MODULE_DESCRIPTION("Raspberry Pi Sense HAT framebuffer driver");
+MODULE_AUTHOR("Serge Schneider <serge@raspberrypi.org>");
+MODULE_LICENSE("GPL");
+
diff --git a/include/linux/mfd/rpisense.h b/include/linux/mfd/rpisense.h
new file mode 100644
index 000000000000..0718b6f0eddb
--- /dev/null
+++ b/include/linux/mfd/rpisense.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Raspberry Pi Sense HAT core driver
+ * http://raspberrypi.org
+ *
+ * Copyright (C) 2015 Raspberry Pi
+ *
+ * Author: Serge Schneider
+ * Adapted for mainline Linux by: Joel Savitz
+ */
+
+#ifndef __LINUX_MFD_RPISENSE_CORE_H_
+#define __LINUX_MFD_RPISENSE_CORE_H_
+
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/gpio/consumer.h>
+#include <linux/platform_device.h>
+
+/*
+ * Register values.
+ */
+#define RPISENSE_FB			0x00
+#define RPISENSE_WAI			0xF0
+#define RPISENSE_VER			0xF1
+#define RPISENSE_KEYS			0xF2
+#define RPISENSE_EE_WP			0xF3
+
+#define RPISENSE_ID			's'
+
+#define SENSEFB_FBIO_IOC_MAGIC 0xF1
+
+#define SENSEFB_FBIOGET_GAMMA _IO(SENSEFB_FBIO_IOC_MAGIC, 0)
+#define SENSEFB_FBIOSET_GAMMA _IO(SENSEFB_FBIO_IOC_MAGIC, 1)
+#define SENSEFB_FBIORESET_GAMMA _IO(SENSEFB_FBIO_IOC_MAGIC, 2)
+
+struct rpisense_fb {
+	struct platform_device *pdev;
+	struct fb_info *info;
+};
+
+
+struct rpisense_js {
+	struct platform_device *pdev;
+	struct input_dev *keys_dev;
+	struct gpio_desc *keys_desc;
+	struct work_struct keys_work_s;
+	int keys_irq;
+};
+
+
+struct rpisense {
+	struct device *dev;
+	struct i2c_client *i2c_client;
+
+	/* Client devices */
+	struct rpisense_js joystick;
+	struct rpisense_fb framebuffer;
+};
+
+struct rpisense *rpisense_get_dev(void);
+s32 rpisense_reg_read(struct rpisense *rpisense, int reg);
+int rpisense_reg_write(struct rpisense *rpisense, int reg, u16 val);
+int rpisense_block_write(struct rpisense *rpisense, const char *buf, int count);
+
+#endif
-- 
2.27.0


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