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Subject[PATCH] platform/x86: dell-uart-backlight: new backlight driver for DELL AIO
Date
The Dell AIO machines released after 2017 come with a UART interface
to communicate with the backlight scalar board. This driver creates
a standard backlight interface and talks to the scalar board through
UART.

In DSDT this uart port will be defined as
Name (_HID, "DELL0501")
Name (_CID, EisaId ("PNP0501")
The 8250 PNP driver will be loaded by default, and this driver uses
"DELL0501" to confirm the uart port is a backlight interface and
leverages the port created by 8250 PNP driver to communicate with
the scalar board.

Signed-off-by: AceLan Kao <acelan.kao@canonical.com>
---
MAINTAINERS | 6 +
drivers/platform/x86/Kconfig | 14 ++
drivers/platform/x86/Makefile | 1 +
drivers/platform/x86/dell-uart-backlight.c | 361 +++++++++++++++++++++++++++++
drivers/platform/x86/dell-uart-backlight.h | 88 +++++++
5 files changed, 470 insertions(+)
create mode 100644 drivers/platform/x86/dell-uart-backlight.c
create mode 100644 drivers/platform/x86/dell-uart-backlight.h

diff --git a/MAINTAINERS b/MAINTAINERS
index d85c089..581cb09 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4013,6 +4013,12 @@ M: Pali Rohár <pali.rohar@gmail.com>
S: Maintained
F: drivers/platform/x86/dell-wmi.c

+DELL AIO UART BACKLIGHT DRIVER
+M: AceLan Kao <acelan.kao@canonical.com>
+L: platform-driver-x86@vger.kernel.org
+S: Maintained
+F: drivers/platform/x86/dell-uart-backlight.c
+
DELTA ST MEDIA DRIVER
M: Hugues Fruchet <hugues.fruchet@st.com>
L: linux-media@vger.kernel.org
diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
index 80b8795..58e26bc 100644
--- a/drivers/platform/x86/Kconfig
+++ b/drivers/platform/x86/Kconfig
@@ -175,6 +175,20 @@ config DELL_RBTN
To compile this driver as a module, choose M here: the module will
be called dell-rbtn.

+config DELL_UART_BACKLIGHT
+ tristate "Dell AIO UART Backlight driver"
+ depends on SERIAL_8250
+ depends on ACPI
+ ---help---
+ Say Y here if you want to support Dell AIO UART backlight interface.
+ The Dell AIO machines released after 2017 come with a UART interface
+ to communicate with the backlight scalar board. This driver creates
+ a standard backlight interface and talks to the scalar board through
+ UART to adjust the AIO screen brightness.
+
+ To compile this driver as a module, choose M here: the module will
+ be called dell_uart_backlight.
+

config FUJITSU_LAPTOP
tristate "Fujitsu Laptop Extras"
diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
index 91cec17..3cf576f 100644
--- a/drivers/platform/x86/Makefile
+++ b/drivers/platform/x86/Makefile
@@ -18,6 +18,7 @@ obj-$(CONFIG_DELL_WMI_AIO) += dell-wmi-aio.o
obj-$(CONFIG_DELL_WMI_LED) += dell-wmi-led.o
obj-$(CONFIG_DELL_SMO8800) += dell-smo8800.o
obj-$(CONFIG_DELL_RBTN) += dell-rbtn.o
+obj-$(CONFIG_DELL_UART_BACKLIGHT) += dell-uart-backlight.o
obj-$(CONFIG_ACER_WMI) += acer-wmi.o
obj-$(CONFIG_ACERHDF) += acerhdf.o
obj-$(CONFIG_HP_ACCEL) += hp_accel.o
diff --git a/drivers/platform/x86/dell-uart-backlight.c b/drivers/platform/x86/dell-uart-backlight.c
new file mode 100644
index 0000000..400be77
--- /dev/null
+++ b/drivers/platform/x86/dell-uart-backlight.c
@@ -0,0 +1,361 @@
+/*
+ * Dell AIO Serial Backlight Driver
+ *
+ * Copyright (C) 2017 AceLan Kao <acelan.kao@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/acpi.h>
+#include <linux/serial_8250.h>
+#include <linux/delay.h>
+#include <linux/backlight.h>
+#include <acpi/video.h>
+
+#include "dell-uart-backlight.h"
+
+struct dell_uart_backlight {
+ struct device *dev;
+ struct backlight_device *dell_uart_bd;
+ struct mutex brightness_mutex;
+ int line;
+ int bl_power;
+};
+struct uart_8250_port *serial8250_get_port(int line);
+struct tty_struct *tty;
+struct file *ftty;
+
+unsigned int (*io_serial_in)(struct uart_port *p, int offset);
+int (*uart_write)(struct tty_struct *tty, const unsigned char *buf, int count);
+int (*uart_chars_in_buffer)(struct tty_struct *tty);
+
+static int dell_uart_write(struct uart_8250_port *up, __u8 *buf, int len)
+{
+ int actual = 0;
+ struct uart_port *port = &up->port;
+
+ tty_port_tty_wakeup(&port->state->port);
+ tty = tty_port_tty_get(&port->state->port);
+ actual = uart_write(tty, buf, len);
+ while (uart_chars_in_buffer(tty)) {
+ udelay(10);
+ }
+
+ return actual;
+}
+
+static int dell_uart_read(struct uart_8250_port *up, __u8 *buf, int len)
+{
+ int i, retry;
+ unsigned long flags;
+
+ spin_lock_irqsave(&up->port.lock, flags);
+ for (i = 0; i < len; i++) {
+ retry = 10;
+ while (!(io_serial_in(&up->port, UART_LSR) & UART_LSR_DR)) {
+ if (--retry == 0)
+ break;
+ mdelay(20);
+ }
+
+ if (retry == 0)
+ break;
+ buf[i] = io_serial_in(&up->port, UART_RX);
+ }
+ spin_unlock_irqrestore(&up->port.lock, flags);
+
+ return i;
+}
+
+static void dell_uart_dump_cmd(const char *func, const char *prefix,
+ const char *cmd, int len)
+{
+ char buf[80];
+
+ snprintf(buf, 80, "dell_uart_backlight:%s:%s", func, prefix);
+ if (len != 0)
+ print_hex_dump_debug(buf, DUMP_PREFIX_NONE,
+ 16, 1, cmd, len, false);
+ else
+ pr_debug("dell_uart_backlight:%s:%sNULL\n", func, prefix);
+
+}
+
+/*
+ * checksum: SUM(Length and Cmd and Data)xor 0xFF)
+ */
+static unsigned char dell_uart_checksum(unsigned char *buf, int len)
+{
+ unsigned char val = 0;
+
+ while (len-- > 0)
+ val += buf[len];
+
+ return val ^ 0xff;
+}
+
+/*
+ * There is no command to get backlight power status,
+ * so we set the backlight power to "on" while initializing,
+ * and then track and report its status by bl_power variable
+ */
+static int dell_uart_get_bl_power(struct dell_uart_backlight *dell_pdata)
+{
+ return dell_pdata->bl_power;
+}
+
+static int dell_uart_set_bl_power(struct backlight_device *bd, int power)
+{
+ struct dell_uart_bl_cmd *bl_cmd =
+ &uart_cmd[DELL_UART_SET_BACKLIGHT_POWER];
+ struct dell_uart_backlight *dell_pdata = bl_get_data(bd);
+ struct uart_8250_port *uart = serial8250_get_port(dell_pdata->line);
+ int rx_len;
+
+ if (power != FB_BLANK_POWERDOWN)
+ power = FB_BLANK_UNBLANK;
+
+ bl_cmd->cmd[2] = power?0:1;
+ bl_cmd->cmd[3] = dell_uart_checksum(bl_cmd->cmd, bl_cmd->tx_len - 1);
+
+ dell_uart_dump_cmd(__func__, "tx: ", bl_cmd->cmd, bl_cmd->tx_len);
+
+ if (mutex_lock_killable(&dell_pdata->brightness_mutex) < 0) {
+ pr_debug("Failed to get mutex_lock");
+ return 0;
+ }
+
+ dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len);
+ rx_len = dell_uart_read(uart, bl_cmd->ret, bl_cmd->rx_len);
+
+ mutex_unlock(&dell_pdata->brightness_mutex);
+
+ dell_uart_dump_cmd(__func__, "rx: ", bl_cmd->ret, rx_len);
+
+ bd->props.power = power;
+ dell_pdata->bl_power = power;
+
+ return 0;
+}
+
+static int dell_uart_get_brightness(struct backlight_device *bd)
+{
+ struct dell_uart_bl_cmd *bl_cmd = &uart_cmd[DELL_UART_GET_BRIGHTNESS];
+ struct dell_uart_backlight *dell_pdata = bl_get_data(bd);
+ struct uart_8250_port *uart = serial8250_get_port(dell_pdata->line);
+ int rx_len, brightness = 0;
+
+ dell_uart_dump_cmd(__func__, "tx: ", bl_cmd->cmd, bl_cmd->tx_len);
+
+ if (mutex_lock_killable(&dell_pdata->brightness_mutex) < 0) {
+ pr_debug("Failed to get mutex_lock");
+ return 0;
+ }
+
+ dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len);
+ rx_len = dell_uart_read(uart, bl_cmd->ret, bl_cmd->rx_len);
+
+ mutex_unlock(&dell_pdata->brightness_mutex);
+
+ dell_uart_dump_cmd(__func__, "rx: ", bl_cmd->ret, rx_len);
+
+ brightness = (unsigned int)bl_cmd->ret[2];
+
+ return brightness;
+}
+
+static int dell_uart_update_status(struct backlight_device *bd)
+{
+ struct dell_uart_bl_cmd *bl_cmd = &uart_cmd[DELL_UART_SET_BRIGHTNESS];
+ struct dell_uart_backlight *dell_pdata = bl_get_data(bd);
+ struct uart_8250_port *uart = serial8250_get_port(dell_pdata->line);
+ int rx_len;
+
+ bl_cmd->cmd[2] = bd->props.brightness;
+ bl_cmd->cmd[3] = dell_uart_checksum(bl_cmd->cmd, bl_cmd->tx_len - 1);
+
+ dell_uart_dump_cmd(__func__, "tx: ", bl_cmd->cmd, bl_cmd->tx_len);
+
+ if (mutex_lock_killable(&dell_pdata->brightness_mutex) < 0) {
+ pr_debug("Failed to get mutex_lock");
+ return 0;
+ }
+
+ dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len);
+ rx_len = dell_uart_read(uart, bl_cmd->ret, bl_cmd->rx_len);
+
+ mutex_unlock(&dell_pdata->brightness_mutex);
+
+ dell_uart_dump_cmd(__func__, "rx: ", bl_cmd->ret, rx_len);
+
+ if (bd->props.power != dell_uart_get_bl_power(dell_pdata))
+ dell_uart_set_bl_power(bd, bd->props.power);
+
+ return 0;
+}
+
+static void dell_uart_show_firmware_ver(struct dell_uart_backlight *dell_pdata)
+{
+ struct dell_uart_bl_cmd *bl_cmd = &uart_cmd[DELL_UART_GET_FIRMWARE_VER];
+ struct uart_8250_port *uart = serial8250_get_port(dell_pdata->line);
+ int rx_len, retry = 10;
+
+ dell_uart_dump_cmd(__func__, "tx: ", bl_cmd->cmd, bl_cmd->tx_len);
+
+ if (mutex_lock_killable(&dell_pdata->brightness_mutex) < 0) {
+ pr_debug("Failed to get mutex_lock");
+ return;
+ }
+
+ dell_uart_write(uart, bl_cmd->cmd, bl_cmd->tx_len);
+ while (retry-- > 0) {
+ /* first byte is data length */
+ dell_uart_read(uart, bl_cmd->ret, 1);
+ rx_len = (int)bl_cmd->ret[0];
+ if (bl_cmd->ret[0] > 80 || bl_cmd->ret[0] <= 0) {
+ pr_debug("Failed to get firmware version\n");
+ if (retry == 0) {
+ mutex_unlock(&dell_pdata->brightness_mutex);
+ return;
+ }
+ msleep(100);
+ continue;
+ }
+
+ dell_uart_read(uart, bl_cmd->ret+1, rx_len-1);
+ break;
+ }
+ mutex_unlock(&dell_pdata->brightness_mutex);
+
+ dell_uart_dump_cmd(__func__, "rx: ", bl_cmd->ret, rx_len);
+
+ pr_debug("Firmare str(%d)= %s\n", (int)bl_cmd->ret[0], bl_cmd->ret+2);
+}
+
+static const struct backlight_ops dell_uart_backlight_ops = {
+ .get_brightness = dell_uart_get_brightness,
+ .update_status = dell_uart_update_status,
+};
+
+static int dell_uart_startup(struct dell_uart_backlight *dell_pdata)
+{
+ struct uart_8250_port *uartp;
+ struct uart_port *port;
+ int ret;
+
+ dell_pdata->line = 0;
+ uartp = serial8250_get_port(dell_pdata->line);
+ port = &uartp->port;
+ ret = port->state->port.ops->activate(&port->state->port, port->state->port.tty);
+ tty = port->state->port.tty;
+ io_serial_in = port->serial_in;
+ uart_write = tty->driver->ops->write;
+ uart_chars_in_buffer = tty->driver->ops->chars_in_buffer;
+
+ return 0;
+}
+
+static int dell_uart_bl_add(struct acpi_device *dev)
+{
+ struct dell_uart_backlight *dell_pdata;
+ struct backlight_properties props;
+ struct backlight_device *dell_uart_bd;
+
+ dell_pdata = kzalloc(sizeof(struct dell_uart_backlight), GFP_KERNEL);
+ dell_pdata->dev = &dev->dev;
+ dell_uart_startup(dell_pdata);
+ dev->driver_data = dell_pdata;
+
+ mutex_init(&dell_pdata->brightness_mutex);
+
+ memset(&props, 0, sizeof(struct backlight_properties));
+ props.type = BACKLIGHT_PLATFORM;
+ props.max_brightness = 100;
+
+ dell_uart_bd = backlight_device_register("dell_uart_backlight",
+ &dev->dev,
+ dell_pdata,
+ &dell_uart_backlight_ops,
+ &props);
+ dell_pdata->dell_uart_bd = dell_uart_bd;
+
+ dell_uart_show_firmware_ver(dell_pdata);
+ dell_uart_set_bl_power(dell_uart_bd, FB_BLANK_UNBLANK);
+ dell_uart_bd->props.brightness = 100;
+ backlight_update_status(dell_uart_bd);
+
+ /* unregister acpi backlight interface */
+ acpi_video_set_dmi_backlight_type(acpi_backlight_vendor);
+
+ return 0;
+}
+
+static int dell_uart_bl_remove(struct acpi_device *dev)
+{
+ struct dell_uart_backlight *dell_pdata = dev->driver_data;
+
+ backlight_device_unregister(dell_pdata->dell_uart_bd);
+
+ return 0;
+}
+
+static int dell_uart_bl_suspend(struct device *dev)
+{
+ filp_close(ftty, NULL);
+ return 0;
+}
+
+static int dell_uart_bl_resume(struct device *dev)
+{
+ ftty = filp_open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY, 0);
+ return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(dell_uart_bl_pm, dell_uart_bl_suspend, dell_uart_bl_resume);
+
+static const struct acpi_device_id dell_uart_bl_ids[] = {
+ {"DELL0501", 0},
+ {"", 0},
+};
+
+static struct acpi_driver dell_uart_backlight_driver = {
+ .name = "Dell AIO serial backlight",
+ .ids = dell_uart_bl_ids,
+ .ops = {
+ .add = dell_uart_bl_add,
+ .remove = dell_uart_bl_remove,
+ },
+ .drv.pm = &dell_uart_bl_pm,
+};
+
+static int __init dell_uart_bl_init(void)
+{
+ ftty = filp_open("/dev/ttyS0", O_RDWR | O_NOCTTY | O_NDELAY, 0);
+
+ return acpi_bus_register_driver(&dell_uart_backlight_driver);
+}
+
+static void __exit dell_uart_bl_exit(void)
+{
+ filp_close(ftty, NULL);
+
+ acpi_bus_unregister_driver(&dell_uart_backlight_driver);
+}
+
+module_init(dell_uart_bl_init);
+module_exit(dell_uart_bl_exit);
+MODULE_DEVICE_TABLE(acpi, dell_uart_bl_ids);
+MODULE_DESCRIPTION("Dell AIO Serial Backlight module");
+MODULE_AUTHOR("AceLan Kao <acelan.kao@canonical.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/platform/x86/dell-uart-backlight.h b/drivers/platform/x86/dell-uart-backlight.h
new file mode 100644
index 0000000..b8bca12
--- /dev/null
+++ b/drivers/platform/x86/dell-uart-backlight.h
@@ -0,0 +1,88 @@
+/*
+ * Dell AIO Serial Backlight Driver
+ *
+ * Copyright (C) 2017 AceLan Kao <acelan.kao@canonical.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _DELL_UART_BACKLIGHT_H_
+#define _DELL_UART_BACKLIGHT_H_
+
+enum {
+ DELL_UART_GET_FIRMWARE_VER,
+ DELL_UART_GET_BRIGHTNESS,
+ DELL_UART_SET_BRIGHTNESS,
+ DELL_UART_SET_BACKLIGHT_POWER,
+};
+
+struct dell_uart_bl_cmd {
+ unsigned char cmd[10];
+ unsigned char ret[80];
+ unsigned short tx_len;
+ unsigned short rx_len;
+};
+
+static struct dell_uart_bl_cmd uart_cmd[] = {
+ /*
+ * Get Firmware Version: Tool uses this command to get firmware version.
+ * Command: 0x6A 0x06 0x8F (Length:3 Type: 0x0A, Cmd:6 Checksum:0x8F)
+ * Return data: 0x0D 0x06 Data checksum (Length:13,Cmd:0x06,
+ * Data :F/W version(APRILIA=APR27-VXXX,PHINE=PHI23-VXXX),
+ * checksum:SUM(Length and Cmd and Data)xor 0xFF .
+ */
+ [DELL_UART_GET_FIRMWARE_VER] = {
+ .cmd = {0x6A, 0x06, 0x8F},
+ .tx_len = 3,
+ },
+ /*
+ * Get Brightness level: Application uses this command for scaler to get brightness.
+ * Command: 0x6A 0x0C 0x89 (Length:3 Type: 0x0A, Cmd:0x0C, Checksum:0x89)
+ * Return data: 0x04 0x0C Data checksum
+ * (Length:4 Cmd: 0x0C Data: brightness level checksum: SUM(Length and Cmd and Data)xor 0xFF)
+ * brightness level which ranges from 0~100.
+ */
+ [DELL_UART_GET_BRIGHTNESS] = {
+ .cmd = {0x6A, 0x0C, 0x89},
+ .ret = {0x04, 0x0C, 0x00, 0x00},
+ .tx_len = 3,
+ .rx_len = 4,
+ },
+ /* Set Brightness level: Application uses this command for scaler to set brightness.
+ * Command: 0x8A 0x0B Byte2 Checksum (Length:4 Type: 0x0A, Cmd:0x0B)
+ * where Byte2 is the brightness level which ranges from 0~100.
+ * Return data: 0x03 0x0B 0xF1(Length:3,Cmd:B,checksum:0xF1)
+ * Scaler must send the 3bytes ack within 1 second when success, other value if error
+ */
+ [DELL_UART_SET_BRIGHTNESS] = {
+ .cmd = {0x8A, 0x0B, 0x0, 0x0},
+ .ret = {0x03, 0x0B, 0xF1},
+ .tx_len = 4,
+ .rx_len = 3,
+ },
+ /*
+ * Screen ON/OFF Control: Application uses this command to control screen ON or OFF.
+ * Command: 0x8A 0x0E Byte2 Checksum (Length:4 Type: 0x0A, Cmd:0x0E) where
+ * Byte2=0 to turn OFF the screen.
+ * Byte2=1 to turn ON the screen
+ * Other value of Byte2 is reserved and invalid.
+ * Return data: 0x03 0x0E 0xEE(Length:3,Cmd:E,checksum:0xEE)
+ */
+ [DELL_UART_SET_BACKLIGHT_POWER] = {
+ .cmd = {0x8A, 0x0E, 0x00, 0x0},
+ .ret = {0x03, 0x0E, 0xEE},
+ .tx_len = 4,
+ .rx_len = 3,
+ },
+};
+
+#endif /* _DELL_UART_BACKLIGHT_H_ */
--
2.7.4
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