This patch add some helpers to control modem lines (CTS/RTS/DSR...) via
GPIO.
This will be useful for many boards which have a serial controller that
only handle CTS/RTS pins (or even just RX/TX).
Signed-off-by: Richard Genoud <richard.genoud@xxxxxxxxx>
---
Documentation/serial/driver | 21 ++++++
drivers/tty/serial/Kconfig | 4 ++
drivers/tty/serial/Makefile | 3 +
drivers/tty/serial/serial_mctrl_gpio.c | 113 +++++++++++++++++++++++++++++++++
drivers/tty/serial/serial_mctrl_gpio.h | 56 ++++++++++++++++
5 files changed, 197 insertions(+)
create mode 100644 drivers/tty/serial/serial_mctrl_gpio.c
create mode 100644 drivers/tty/serial/serial_mctrl_gpio.h
diff --git a/Documentation/serial/driver b/Documentation/serial/driver
index c3a7689a90e6..b33f0f9e1b8e 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -429,3 +429,24 @@ thus:
struct uart_port port;
int my_stuff;
};
+
+Modem control lines via GPIO
+----------------------------
+
+Some helpers are provided in order to set/get modem control lines via GPIO.
+
+mctrl_gpio_init(dev, gpios):
+ This will get the {cts,rts,...}-gpios from device tree if they are
+ present and request them, set direction etc.
+
+mctrl_gpio_free(gpios):
+ This will free the requested gpios in mctrl_gpio_init().
+
+mctrl_gpio_set(gpios, mctrl):
+ This will sets the gpios according to the mctrl state.
+
+mctrl_gpio_get(gpios, mctrl):
+ This will update mctrl with the gpios values.
+
+get_mctrl_gpio_name(mctrl_gpio_idx):
+ Returns a name associated to the GPIO modem line.
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index a3815eaed421..58c54d7eae53 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1509,4 +1509,8 @@ config SERIAL_ST_ASC_CONSOLE
endmenu
+config SERIAL_MCTRL_GPIO
+ def_bool y
+ depends on GPIOLIB
+
endif # TTY
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index 3680854fef41..bcf31da267dd 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -87,3 +87,6 @@ obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
obj-$(CONFIG_SERIAL_ARC) += arc_uart.o
obj-$(CONFIG_SERIAL_RP2) += rp2.o
obj-$(CONFIG_SERIAL_FSL_LPUART) += fsl_lpuart.o
+
+# GPIOLIB helpers for modem control lines
+obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
new file mode 100644
index 000000000000..ddcc7538f487
--- /dev/null
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -0,0 +1,113 @@
+/*
+ * Helpers for controlling modem lines via GPIO
+ *
+ * Copyright (C) 2014 Paratronic S.A.
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <uapi/asm-generic/termios.h>
+
+#include "serial_mctrl_gpio.h"
+
+static const char *mctrl_gpio_of_names[UART_GPIO_MAX] = {
+ "cts", "dsr", "dcd", "ri", "rts", "dtr"
+};
+
+const char *get_mctrl_gpio_name(enum mctrl_gpio_idx idx)
+{
+ return mctrl_gpio_of_names[idx];
+}
+EXPORT_SYMBOL_GPL(get_mctrl_gpio_name);
+
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
+{
+ if (!IS_ERR_OR_NULL(gpios->gpio[UART_GPIO_RTS]))
+ gpiod_set_value(gpios->gpio[UART_GPIO_RTS],
+ !!(mctrl & TIOCM_RTS));
+
+ if (!IS_ERR_OR_NULL(gpios->gpio[UART_GPIO_DTR]))
+ gpiod_set_value(gpios->gpio[UART_GPIO_DTR],
+ !!(mctrl & TIOCM_DTR));
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_set);
+
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
+{
+ if (!IS_ERR_OR_NULL(gpios->gpio[UART_GPIO_CTS])) {
+ if (gpiod_get_value(gpios->gpio[UART_GPIO_CTS]))
+ *mctrl |= TIOCM_CTS;
+ else
+ *mctrl &= ~TIOCM_CTS;
+ }
+
+ if (!IS_ERR_OR_NULL(gpios->gpio[UART_GPIO_DSR])) {
+ if (gpiod_get_value(gpios->gpio[UART_GPIO_DSR]))
+ *mctrl |= TIOCM_DSR;
+ else
+ *mctrl &= ~TIOCM_DSR;
+ }
+
+ if (!IS_ERR_OR_NULL(gpios->gpio[UART_GPIO_RI])) {
+ if (gpiod_get_value(gpios->gpio[UART_GPIO_RI]))
+ *mctrl |= TIOCM_RI;
+ else
+ *mctrl &= ~TIOCM_RI;
+ }
+
+ if (!IS_ERR_OR_NULL(gpios->gpio[UART_GPIO_DCD])) {
+ if (gpiod_get_value(gpios->gpio[UART_GPIO_DCD]))
+ *mctrl |= TIOCM_CD;
+ else
+ *mctrl &= ~TIOCM_CD;
+ }
+
+ return *mctrl;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_get);
+
+int mctrl_gpio_init(struct device *dev, struct mctrl_gpios *gpios)
+{
+ enum mctrl_gpio_idx i;
+ int err = 0;
+ int ret = 0;
+
+ for (i = UART_GPIO_MIN; i < UART_GPIO_MAX; i++) {
+ gpios->gpio[i] = gpiod_get(dev, mctrl_gpio_of_names[i]);
+
+ /*
+ * The GPIOs are maybe not all filled,
+ * this is not an error.
+ */
+ if (IS_ERR_OR_NULL(gpios->gpio[i]))
+ continue;
+
+ if (i < UART_GPIO_MAX_INPUT)
+ err = gpiod_direction_input(gpios->gpio[i]);
+ else
+ err = gpiod_direction_output(gpios->gpio[i], 0);
+ if (err) {
+ dev_err(dev, "Unable to set direction for %s GPIO",
+ mctrl_gpio_of_names[i]);
+ gpiod_put(gpios->gpio[i]);
+ gpios->gpio[i] = NULL;
+ ret--;
+ }
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_init);
+
+void mctrl_gpio_free(struct mctrl_gpios *gpios)
+{
+ enum mctrl_gpio_idx i;
+
+ for (i = UART_GPIO_MIN; i < UART_GPIO_MAX; i++)
+ if (!IS_ERR_OR_NULL(gpios->gpio[i])) {
+ gpiod_put(gpios->gpio[i]);
+ gpios->gpio[i] = NULL;
+ }
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_free);
diff --git a/drivers/tty/serial/serial_mctrl_gpio.h b/drivers/tty/serial/serial_mctrl_gpio.h
new file mode 100644
index 000000000000..5b8be48f6442
--- /dev/null
+++ b/drivers/tty/serial/serial_mctrl_gpio.h
@@ -0,0 +1,56 @@
+/*
+ * Helpers for controlling modem lines via GPIO
+ *
+ * Copyright (C) 2014 Paratronic S.A.
+ *
+ */
+
+#ifndef __SERIAL_MCTRL_GPIO__
+#define __SERIAL_MCTRL_GPIO__
+
+#include <linux/gpio/consumer.h>
+
+enum mctrl_gpio_idx {
+ UART_GPIO_MIN = 0,
+ UART_GPIO_CTS = 0,
+ UART_GPIO_DSR = 1,
+ UART_GPIO_DCD = 2,
+ UART_GPIO_RI = 3,
+ UART_GPIO_MAX_INPUT = 4,
+ UART_GPIO_RTS = 4,
+ UART_GPIO_DTR = 5,
+ UART_GPIO_MAX,
+};
+
+struct mctrl_gpios {
+ struct gpio_desc *gpio[UART_GPIO_MAX];
+};
+
+/*
+ * Names of the modem lines (cts, dsr, dcd...)
+ */
+const char *get_mctrl_gpio_name(enum mctrl_gpio_idx idx);
+
+/*
+ * Set state of the modem control output lines via GPIOs.
+ */
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl);
+
+/*
+ * Get state of the modem control output lines from GPIOs.
+ * The mctrl flags are updated and returned.
+ */
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl);
+
+/*
+ * Request and set direction of modem control lines GPIOs.
+ * Returns 0 if ok, -nb_err if setting direction failed.
+ */
+int mctrl_gpio_init(struct device *dev, struct mctrl_gpios *gpios);
+
+/*
+ * Free all modem control lines GPIOs
+ */
+void mctrl_gpio_free(struct mctrl_gpios *gpios);
+
+#endif
--
1.8.5
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