[PATCH 3/5] tty/serial: Add GPIOLIB helpers for controlling modem lines
Richard Genoud
richard.genoud at gmail.com
Fri Apr 25 07:52:39 PDT 2014
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 at gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
Documentation/serial/driver | 25 ++++++
drivers/tty/serial/Kconfig | 3 +
drivers/tty/serial/Makefile | 3 +
drivers/tty/serial/serial_mctrl_gpio.c | 143 +++++++++++++++++++++++++++++++++
drivers/tty/serial/serial_mctrl_gpio.h | 110 +++++++++++++++++++++++++
5 files changed, 284 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..3bba1aeb799c 100644
--- a/Documentation/serial/driver
+++ b/Documentation/serial/driver
@@ -429,3 +429,28 @@ 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, idx):
+ This will get the {cts,rts,...}-gpios from device tree if they are
+ present and request them, set direction etc, and return an
+ allocated structure. devm_* functions are used, so there's no need
+ to call mctrl_gpio_free().
+
+mctrl_gpio_free(dev, gpios):
+ This will free the requested gpios in mctrl_gpio_init().
+ As devm_* function are used, there's generally no need to call
+ this function.
+
+mctrl_gpio_to_gpiod(gpios, gidx)
+ This returns the gpio structure associated to the modem line index.
+
+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.
diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 5d9b01aa54f4..95afd310d18e 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1510,4 +1510,7 @@ config SERIAL_ST_ASC_CONSOLE
endmenu
+config SERIAL_MCTRL_GPIO
+ tristate
+
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..bf9560ffe3f4
--- /dev/null
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -0,0 +1,143 @@
+/*
+ * Helpers for controlling modem lines via GPIO
+ *
+ * Copyright (C) 2014 Paratronic S.A.
+ *
+ * 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/err.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <uapi/asm-generic/termios.h>
+
+#include "serial_mctrl_gpio.h"
+
+struct mctrl_gpios {
+ struct gpio_desc *gpio[UART_GPIO_MAX];
+};
+
+static const struct {
+ const char *name;
+ unsigned int mctrl;
+ bool dir_out;
+} mctrl_gpios_desc[UART_GPIO_MAX] = {
+ { "cts", TIOCM_CTS, false, },
+ { "dsr", TIOCM_DSR, false, },
+ { "dcd", TIOCM_CD, false, },
+ { "rng", TIOCM_RNG, false, },
+ { "rts", TIOCM_RTS, true, },
+ { "dtr", TIOCM_DTR, true, },
+ { "out1", TIOCM_OUT1, true, },
+ { "out2", TIOCM_OUT2, true, },
+};
+
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
+{
+ enum mctrl_gpio_idx i;
+
+ if (IS_ERR_OR_NULL(gpios))
+ return;
+
+ for (i = 0; i < UART_GPIO_MAX; i++)
+ if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
+ mctrl_gpios_desc[i].dir_out)
+ gpiod_set_value(gpios->gpio[i],
+ !!(mctrl & mctrl_gpios_desc[i].mctrl));
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_set);
+
+struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
+ enum mctrl_gpio_idx gidx)
+{
+ if (!IS_ERR_OR_NULL(gpios) && !IS_ERR_OR_NULL(gpios->gpio[gidx]))
+ return gpios->gpio[gidx];
+ else
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
+
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
+{
+ enum mctrl_gpio_idx i;
+
+ /*
+ * return it unchanged if the structure is not allocated
+ */
+ if (IS_ERR_OR_NULL(gpios))
+ return *mctrl;
+
+ for (i = 0; i < UART_GPIO_MAX; i++) {
+ if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
+ !mctrl_gpios_desc[i].dir_out) {
+ if (gpiod_get_value(gpios->gpio[i]))
+ *mctrl |= mctrl_gpios_desc[i].mctrl;
+ else
+ *mctrl &= ~mctrl_gpios_desc[i].mctrl;
+ }
+ }
+
+ return *mctrl;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_get);
+
+struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
+{
+ struct mctrl_gpios *gpios;
+ enum mctrl_gpio_idx i;
+ int err;
+
+ gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
+ if (!gpios)
+ return ERR_PTR(-ENOMEM);
+
+ for (i = 0; i < UART_GPIO_MAX; i++) {
+ gpios->gpio[i] = devm_gpiod_get_index(dev,
+ mctrl_gpios_desc[i].name,
+ idx);
+
+ /*
+ * The GPIOs are maybe not all filled,
+ * this is not an error.
+ */
+ if (IS_ERR_OR_NULL(gpios->gpio[i]))
+ continue;
+
+ if (mctrl_gpios_desc[i].dir_out)
+ err = gpiod_direction_output(gpios->gpio[i], 0);
+ else
+ err = gpiod_direction_input(gpios->gpio[i]);
+ if (err) {
+ dev_dbg(dev, "Unable to set direction for %s GPIO",
+ mctrl_gpios_desc[i].name);
+ devm_gpiod_put(dev, gpios->gpio[i]);
+ gpios->gpio[i] = NULL;
+ }
+ }
+
+ return gpios;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_init);
+
+void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
+{
+ enum mctrl_gpio_idx i;
+
+ if (IS_ERR_OR_NULL(gpios))
+ return;
+
+ for (i = 0; i < UART_GPIO_MAX; i++)
+ if (!IS_ERR_OR_NULL(gpios->gpio[i]))
+ devm_gpiod_put(dev, gpios->gpio[i]);
+ devm_kfree(dev, gpios);
+}
+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..400ba0494a17
--- /dev/null
+++ b/drivers/tty/serial/serial_mctrl_gpio.h
@@ -0,0 +1,110 @@
+/*
+ * Helpers for controlling modem lines via GPIO
+ *
+ * Copyright (C) 2014 Paratronic S.A.
+ *
+ * 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 __SERIAL_MCTRL_GPIO__
+#define __SERIAL_MCTRL_GPIO__
+
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+
+enum mctrl_gpio_idx {
+ UART_GPIO_CTS,
+ UART_GPIO_DSR,
+ UART_GPIO_DCD,
+ UART_GPIO_RNG,
+ UART_GPIO_RI = UART_GPIO_RNG,
+ UART_GPIO_RTS,
+ UART_GPIO_DTR,
+ UART_GPIO_OUT1,
+ UART_GPIO_OUT2,
+ UART_GPIO_MAX,
+};
+
+/*
+ * Opaque descriptor for modem lines controlled by GPIOs
+ */
+struct mctrl_gpios;
+
+#ifdef CONFIG_GPIOLIB
+
+/*
+ * 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);
+
+/*
+ * Returns the associated struct gpio_desc to the modem line gidx
+ */
+struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
+ enum mctrl_gpio_idx gidx);
+
+/*
+ * Request and set direction of modem control lines GPIOs.
+ * devm_* functions are used, so there's no need to call mctrl_gpio_free().
+ * Returns a pointer to the allocated mctrl structure if ok, -ENOMEM on
+ * allocation error.
+ */
+struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx);
+
+/*
+ * Free the mctrl_gpios structure.
+ * Normally, this function will not be called, as the GPIOs will
+ * be disposed of by the resource management code.
+ */
+void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios);
+
+#else /* GPIOLIB */
+
+static inline
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
+{
+}
+
+static inline
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
+{
+ return *mctrl;
+}
+
+static inline
+struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
+ enum mctrl_gpio_idx gidx)
+{
+ return ERR_PTR(-ENOSYS);
+}
+
+static inline
+struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
+{
+ return ERR_PTR(-ENOSYS);
+}
+
+static inline
+void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
+{
+}
+
+#endif /* GPIOLIB */
+
+#endif
--
1.8.5.5
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