1 files changed, 301 insertions, 0 deletions
diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
new file mode 100644
index 000000000..af0412a78
--- /dev/null
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -0,0 +1,301 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Helpers for controlling modem lines via GPIO
+ *
+ * Copyright (C) 2014 Paratronic S.A.
+ */
+
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/irq.h>
+#include <linux/gpio/consumer.h>
+#include <linux/termios.h>
+#include <linux/serial_core.h>
+#include <linux/module.h>
+#include <linux/property.h>
+
+#include "serial_mctrl_gpio.h"
+
+struct mctrl_gpios {
+	struct uart_port *port;
+	struct gpio_desc *gpio[UART_GPIO_MAX];
+	int irq[UART_GPIO_MAX];
+	unsigned int mctrl_prev;
+	bool mctrl_on;
+};
+
+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, },
+};
+
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
+{
+	enum mctrl_gpio_idx i;
+	struct gpio_desc *desc_array[UART_GPIO_MAX];
+	int value_array[UART_GPIO_MAX];
+	unsigned int count = 0;
+
+	if (gpios == NULL)
+		return;
+
+	for (i = 0; i < UART_GPIO_MAX; i++)
+		if (gpios->gpio[i] && mctrl_gpios_desc[i].dir_out) {
+			desc_array[count] = gpios->gpio[i];
+			value_array[count] = !!(mctrl & mctrl_gpios_desc[i].mctrl);
+			count++;
+		}
+	gpiod_set_array_value(count, desc_array, value_array);
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_set);
+
+struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
+				      enum mctrl_gpio_idx gidx)
+{
+	if (gpios == NULL)
+		return NULL;
+
+	return gpios->gpio[gidx];
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
+
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
+{
+	enum mctrl_gpio_idx i;
+
+	if (gpios == NULL)
+		return *mctrl;
+
+	for (i = 0; i < UART_GPIO_MAX; i++) {
+		if (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);
+
+unsigned int
+mctrl_gpio_get_outputs(struct mctrl_gpios *gpios, unsigned int *mctrl)
+{
+	enum mctrl_gpio_idx i;
+
+	if (gpios == NULL)
+		return *mctrl;
+
+	for (i = 0; i < UART_GPIO_MAX; i++) {
+		if (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_outputs);
+
+struct mctrl_gpios *mctrl_gpio_init_noauto(struct device *dev, unsigned int idx)
+{
+	struct mctrl_gpios *gpios;
+	enum mctrl_gpio_idx i;
+
+	gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
+	if (!gpios)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < UART_GPIO_MAX; i++) {
+		enum gpiod_flags flags;
+		char *gpio_str;
+		bool present;
+
+		/* Check if GPIO property exists and continue if not */
+		gpio_str = kasprintf(GFP_KERNEL, "%s-gpios",
+				     mctrl_gpios_desc[i].name);
+		if (!gpio_str)
+			continue;
+
+		present = device_property_present(dev, gpio_str);
+		kfree(gpio_str);
+		if (!present)
+			continue;
+
+		if (mctrl_gpios_desc[i].dir_out)
+			flags = GPIOD_OUT_LOW;
+		else
+			flags = GPIOD_IN;
+
+		gpios->gpio[i] =
+			devm_gpiod_get_index_optional(dev,
+						      mctrl_gpios_desc[i].name,
+						      idx, flags);
+
+		if (IS_ERR(gpios->gpio[i]))
+			return ERR_CAST(gpios->gpio[i]);
+	}
+
+	return gpios;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_init_noauto);
+
+#define MCTRL_ANY_DELTA (TIOCM_RI | TIOCM_DSR | TIOCM_CD | TIOCM_CTS)
+static irqreturn_t mctrl_gpio_irq_handle(int irq, void *context)
+{
+	struct mctrl_gpios *gpios = context;
+	struct uart_port *port = gpios->port;
+	u32 mctrl = gpios->mctrl_prev;
+	u32 mctrl_diff;
+	unsigned long flags;
+
+	mctrl_gpio_get(gpios, &mctrl);
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	mctrl_diff = mctrl ^ gpios->mctrl_prev;
+	gpios->mctrl_prev = mctrl;
+
+	if (mctrl_diff & MCTRL_ANY_DELTA && port->state != NULL) {
+		if ((mctrl_diff & mctrl) & TIOCM_RI)
+			port->icount.rng++;
+
+		if ((mctrl_diff & mctrl) & TIOCM_DSR)
+			port->icount.dsr++;
+
+		if (mctrl_diff & TIOCM_CD)
+			uart_handle_dcd_change(port, mctrl & TIOCM_CD);
+
+		if (mctrl_diff & TIOCM_CTS)
+			uart_handle_cts_change(port, mctrl & TIOCM_CTS);
+
+		wake_up_interruptible(&port->state->port.delta_msr_wait);
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+struct mctrl_gpios *mctrl_gpio_init(struct uart_port *port, unsigned int idx)
+{
+	struct mctrl_gpios *gpios;
+	enum mctrl_gpio_idx i;
+
+	gpios = mctrl_gpio_init_noauto(port->dev, idx);
+	if (IS_ERR(gpios))
+		return gpios;
+
+	gpios->port = port;
+
+	for (i = 0; i < UART_GPIO_MAX; ++i) {
+		int ret;
+
+		if (!gpios->gpio[i] || mctrl_gpios_desc[i].dir_out)
+			continue;
+
+		ret = gpiod_to_irq(gpios->gpio[i]);
+		if (ret <= 0) {
+			dev_err(port->dev,
+				"failed to find corresponding irq for %s (idx=%d, err=%d)\n",
+				mctrl_gpios_desc[i].name, idx, ret);
+			return ERR_PTR(ret);
+		}
+		gpios->irq[i] = ret;
+
+		/* irqs should only be enabled in .enable_ms */
+		irq_set_status_flags(gpios->irq[i], IRQ_NOAUTOEN);
+
+		ret = devm_request_irq(port->dev, gpios->irq[i],
+				       mctrl_gpio_irq_handle,
+				       IRQ_TYPE_EDGE_BOTH, dev_name(port->dev),
+				       gpios);
+		if (ret) {
+			/* alternatively implement polling */
+			dev_err(port->dev,
+				"failed to request irq for %s (idx=%d, err=%d)\n",
+				mctrl_gpios_desc[i].name, idx, ret);
+			return ERR_PTR(ret);
+		}
+	}
+
+	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 (gpios == NULL)
+		return;
+
+	for (i = 0; i < UART_GPIO_MAX; i++) {
+		if (gpios->irq[i])
+			devm_free_irq(gpios->port->dev, gpios->irq[i], gpios);
+
+		if (gpios->gpio[i])
+			devm_gpiod_put(dev, gpios->gpio[i]);
+	}
+	devm_kfree(dev, gpios);
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_free);
+
+void mctrl_gpio_enable_ms(struct mctrl_gpios *gpios)
+{
+	enum mctrl_gpio_idx i;
+
+	if (gpios == NULL)
+		return;
+
+	/* .enable_ms may be called multiple times */
+	if (gpios->mctrl_on)
+		return;
+
+	gpios->mctrl_on = true;
+
+	/* get initial status of modem lines GPIOs */
+	mctrl_gpio_get(gpios, &gpios->mctrl_prev);
+
+	for (i = 0; i < UART_GPIO_MAX; ++i) {
+		if (!gpios->irq[i])
+			continue;
+
+		enable_irq(gpios->irq[i]);
+	}
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_enable_ms);
+
+void mctrl_gpio_disable_ms(struct mctrl_gpios *gpios)
+{
+	enum mctrl_gpio_idx i;
+
+	if (gpios == NULL)
+		return;
+
+	if (!gpios->mctrl_on)
+		return;
+
+	gpios->mctrl_on = false;
+
+	for (i = 0; i < UART_GPIO_MAX; ++i) {
+		if (!gpios->irq[i])
+			continue;
+
+		disable_irq(gpios->irq[i]);
+	}
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_disable_ms);
+
+MODULE_LICENSE("GPL");