diff options
Diffstat (limited to 'drivers/tty/serial/serial_mctrl_gpio.c')
| -rw-r--r-- | drivers/tty/serial/serial_mctrl_gpio.c | 302 |
1 files changed, 302 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..fb4781292 --- /dev/null +++ b/drivers/tty/serial/serial_mctrl_gpio.c @@ -0,0 +1,302 @@ +// 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; + enum gpiod_flags flags; +} mctrl_gpios_desc[UART_GPIO_MAX] = { + { "cts", TIOCM_CTS, GPIOD_IN, }, + { "dsr", TIOCM_DSR, GPIOD_IN, }, + { "dcd", TIOCM_CD, GPIOD_IN, }, + { "rng", TIOCM_RNG, GPIOD_IN, }, + { "rts", TIOCM_RTS, GPIOD_OUT_LOW, }, + { "dtr", TIOCM_DTR, GPIOD_OUT_LOW, }, +}; + +static bool mctrl_gpio_flags_is_dir_out(unsigned int idx) +{ + return mctrl_gpios_desc[idx].flags & GPIOD_FLAGS_BIT_DIR_OUT; +} + +void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl) +{ + enum mctrl_gpio_idx i; + struct gpio_desc *desc_array[UART_GPIO_MAX]; + DECLARE_BITMAP(values, UART_GPIO_MAX); + unsigned int count = 0; + + if (gpios == NULL) + return; + + for (i = 0; i < UART_GPIO_MAX; i++) + if (gpios->gpio[i] && mctrl_gpio_flags_is_dir_out(i)) { + desc_array[count] = gpios->gpio[i]; + __assign_bit(count, values, + mctrl & mctrl_gpios_desc[i].mctrl); + count++; + } + gpiod_set_array_value(count, desc_array, NULL, values); +} +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_gpio_flags_is_dir_out(i)) { + 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_gpio_flags_is_dir_out(i)) { + 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++) { + 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; + + gpios->gpio[i] = + devm_gpiod_get_index_optional(dev, + mctrl_gpios_desc[i].name, + idx, + mctrl_gpios_desc[i].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_gpio_flags_is_dir_out(i)) + 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"); |