Add Hynitron cstxxx Touchscreen

From: Chris Morgan <[email protected]>

Add support for the Hynitron cst3xx controller found on devices such as the Anbernic RG353P and RG353V (the Hynitron CST340). This driver was built from sources provided by Hynitron to Anbernic (possibly via Rockchip as an intermediary) and marked as GPLv2 in the code. This driver was written strictly for the cst3xx series, but in most places was left somewhat generic so support could be easily added to other devices in the future.

Signed-off-by Chris Morgan <[email protected]>

---
 drivers/input/touchscreen/Kconfig           |  12 +
 drivers/input/touchscreen/Makefile          |   1 +
 drivers/input/touchscreen/hynitron_cstxxx.c | 505 ++++++++++++++++++++
 3 files changed, 518 insertions(+)
 create mode 100644 drivers/input/touchscreen/hynitron_cstxxx.c

drivers/input/touchscreen/Kconfig +12 -0

index dc90a3ea51ee..46b158c04c7b 100644
@@ -422,6 +422,18 @@ config TOUCHSCREEN_HYCON_HY46XX
 	  To compile this driver as a module, choose M here: the
 	  module will be called hycon-hy46xx.
 
+config TOUCHSCREEN_HYNITRON_CSTXXX
+	tristate "Hynitron touchscreen support"
+	depends on I2C
+	help
+	  Say Y here if you have a touchscreen using a Hynitron
+	  touchscreen controller.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called hynitron-cstxxx.
+
 config TOUCHSCREEN_ILI210X
 	tristate "Ilitek ILI210X based touchscreen"
 	depends on I2C

drivers/input/touchscreen/Makefile +1 -0

index 557f84fd2075..43860ca19b98 100644
@@ -47,6 +47,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
 obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
 obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
 obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
+obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
 obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
 obj-$(CONFIG_TOUCHSCREEN_ILITEK)	+= ilitek_ts_i2c.o
 obj-$(CONFIG_TOUCHSCREEN_IMAGIS)	+= imagis.o

drivers/input/touchscreen/hynitron_cstxxx.c new file +5 -0

new file mode 100644
index 000000000000..ca39e8a775b7
@@ -0,0 +1,505 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Driver for Hynitron cstxxx Touchscreen
+ *
+ *  Copyright (c) 2022 Chris Morgan <[email protected]>

drivers/input/touchscreen/hynitron_cstxxx.c new file +16 -0

+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/input/mt.h>
+#include <linux/input/touchscreen.h>
+#include <linux/module.h>
+
+/* Per chip data */
+struct hynitron_ts_chip_data {
+	unsigned int max_touch_num;
+	u32 ic_chkcode;
+	int (*firmware_info)(struct i2c_client *client);
+	int (*bootloader_enter)(struct i2c_client *client);
+	int (*init_input)(struct i2c_client *client);
+	void (*report_touch)(struct i2c_client *client);

drivers/input/touchscreen/hynitron_cstxxx.c new file +84 -0

+};
+
+/*
+ * Since I have no datasheet, these values are guessed and/or assumed
+ * based on observation and testing.
+ */
+#define CST3XX_FIRMWARE_INFO_START_CMD		0x01d1
+#define CST3XX_FIRMWARE_INFO_END_CMD		0x09d1
+#define CST3XX_FIRMWARE_CHK_CODE_REG		0xfcd1
+#define CST3XX_FIRMWARE_VERSION_REG		0x08d2
+#define CST3XX_FIRMWARE_VER_INVALID_VAL		0xa5a5a5a5
+
+#define CST3XX_BOOTLDR_PROG_CMD			0xaa01a0
+#define CST3XX_BOOTLDR_PROG_CHK_REG		0x02a0
+#define CST3XX_BOOTLDR_CHK_VAL			0xac
+
+#define CST3XX_TOUCH_DATA_PART_REG		0x00d0
+#define CST3XX_TOUCH_DATA_FULL_REG		0x07d0
+#define CST3XX_TOUCH_DATA_CHK_VAL		0xab
+#define CST3XX_TOUCH_DATA_TOUCH_VAL		0x03
+#define CST3XX_TOUCH_DATA_STOP_CMD		0xab00d0
+#define CST3XX_TOUCH_COUNT_MASK			GENMASK(6, 0)
+
+
+/*
+ * Hard coded reset delay value of 20ms not IC dependent in
+ * vendor driver.
+ */
+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);
+}
+
+static irqreturn_t hyn_interrupt_handler(int irq, void *dev_id)
+{
+	struct i2c_client *client = dev_id;
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	ts_data->pdata->report_touch(client);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * The vendor driver would retry twice before failing to read or write
+ * to the i2c device.
+ */
+
+static int cst3xx_i2c_write(struct i2c_client *client,
+			    unsigned char *buf, int len)
+{
+	int ret;
+	int retries = 0;
+
+	while (retries < 2) {
+		ret = i2c_master_send(client, buf, len);
+		if (ret == len)
+			return 0;
+		if (ret <= 0)
+			retries++;
+		else
+			break;
+	}
+
+	return ret < 0 ? ret : -EIO;
+}
+
+static int cst3xx_i2c_read_register(struct i2c_client *client, u16 reg,
+				    u8 *val, u16 len)
+{
+	__le16 buf = cpu_to_le16(reg);
+	struct i2c_msg msgs[] = {
+		{
+			.addr = client->addr,
+			.flags = 0,
+			.len = 2,
+			.buf = (u8 *)&buf,
+		},

drivers/input/touchscreen/hynitron_cstxxx.c new file +15 -0

+	if (ret >= 0)
+		ret = (ret == ARRAY_SIZE(msgs) ? 0 : -EIO);
+
+	if (ret)
+		dev_err(&client->dev,
+			"Error reading %d bytes from 0x%04x: %d\n",
+			len, reg, ret);
+
+	return ret;
+}
+
+static int cst3xx_firmware_info(struct i2c_client *client)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+	int ret;

Hi Chris,

drivers/input/touchscreen/hynitron_cstxxx.c line 78

Quoted 9 lines · Chris Morgan

drivers/input/touchscreen/hynitron_cstxxx.c new file +9 -0

+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);

Just wanted to ask - you do not really want to spin for 20+ msecs here, right? I think changing mdelay() to msleep()/usleep() should be OK throughout the driver...

Thanks.

Signature · 1 line

Dmitry

Quoted 16 lines · Dmitry Torokhov

Hi Chris,

drivers/input/touchscreen/hynitron_cstxxx.c line 78

Quoted 9 lines · Chris Morgan

drivers/input/touchscreen/hynitron_cstxxx.c new file +9 -0

+static void hyn_reset_proc(struct i2c_client *client, int delay)
+{
+	struct hynitron_ts_data *ts_data = i2c_get_clientdata(client);
+
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 1);
+	mdelay(20);
+	gpiod_set_value_cansleep(ts_data->reset_gpio, 0);
+	if (delay)
+		mdelay(delay);

Just wanted to ask - you do not really want to spin for 20+ msecs here, right? I think changing mdelay() to msleep()/usleep() should be OK throughout the driver...

I just tested changing all instances of mdelay to msleep and msleep works just fine. Do you want me to resubmit or can you change that as well?