sc16is7xx driver does not transmit with crtscts enabled from linux

[kchaves]

So first I'm using the 4.9 driver in the 3.14 kernel, the major changes I had to make were minor renames kthread_queue to queue_kthread and added a couple of header files.  I also needed to add a gpio-enable entry to toggle the chip enable pin, I'm not sure if there is a generic way of doing it in the device tree. It is connected to a bluetooth module via uart and cts/rts both hooked up. 

When using 'stty -F /dev/ttySC0 115200 crtscts', linux will wait for something before calling its start_tx in the serial core. I have not been able to dig deep enough into this problem but I got around the issue by disabling crtscts in the patching tool and forcing auto rts/cts to be enabled for line 0. 

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c

index 793395451982..bceeaf6f33e6 100644

--- a/drivers/tty/serial/sc16is7xx.c

+++ b/drivers/tty/serial/sc16is7xx.c

@@ -29,6 +29,8 @@

#include <linux/tty_flip.h>

#include <linux/spi/spi.h>

#include <linux/uaccess.h>

+#include <linux/sched/rt.h>

+#include <linux/of_gpio.h>

#define SC16IS7XX_NAME         "sc16is7xx"

#define SC16IS7XX_MAX_DEVS     8

@@ -333,6 +335,9 @@ struct sc16is7xx_port {

   struct task_struct      *kworker_task;

   struct kthread_work     irq_work;

   struct sc16is7xx_one        p[0];

+

+   unsigned long enable_gpio_flags;

+   int enable_gpio;

};

static unsigned long sc16is7xx_lines;

@@ -708,7 +713,7 @@ static irqreturn_t sc16is7xx_irq(int irq, void *dev_id)

{

   struct sc16is7xx_port *s = (struct sc16is7xx_port *)dev_id;

-   kthread_queue_work(&s->kworker, &s->irq_work);

+   queue_kthread_work(&s->kworker, &s->irq_work);

   return IRQ_HANDLED;

}

@@ -784,7 +789,7 @@ static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit)

   one->config.flags |= SC16IS7XX_RECONF_IER;

   one->config.ier_clear |= bit;

-   kthread_queue_work(&s->kworker, &one->reg_work);

+   queue_kthread_work(&s->kworker, &one->reg_work);

}

static void sc16is7xx_stop_tx(struct uart_port *port)

@@ -802,7 +807,7 @@ static void sc16is7xx_start_tx(struct uart_port *port)

   struct sc16is7xx_port *s = dev_get_drvdata(port->dev);

   struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);

-   kthread_queue_work(&s->kworker, &one->tx_work);

+   queue_kthread_work(&s->kworker, &one->tx_work);

}

static unsigned int sc16is7xx_tx_empty(struct uart_port *port)

@@ -828,7 +833,7 @@ static void sc16is7xx_set_mctrl(struct uart_port *port, unsigned int mctrl)

   struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);

   one->config.flags |= SC16IS7XX_RECONF_MD;

-   kthread_queue_work(&s->kworker, &one->reg_work);

+   queue_kthread_work(&s->kworker, &one->reg_work);

}

static void sc16is7xx_break_ctl(struct uart_port *port, int break_state)

@@ -903,9 +908,18 @@ static void sc16is7xx_set_termios(struct uart_port *port,

   regcache_cache_bypass(s->regmap, true);

   sc16is7xx_port_write(port, SC16IS7XX_XON1_REG, termios->c_cc[VSTART]);

   sc16is7xx_port_write(port, SC16IS7XX_XOFF1_REG, termios->c_cc[VSTOP]);

-   if (termios->c_cflag & CRTSCTS)

+

+

+   /*

+       This is a hack, the linux serial core driver will wait for something

+       to know if the chip is ready to send... it never is so just force it

+       to be enabled for port 0, the rest of the bluetooth software will have

+       to disable CRTSCTS from now on.

+   */

+   if (termios->c_cflag & CRTSCTS || 0 == sc16is7xx_line(port))

       flow |= SC16IS7XX_EFR_AUTOCTS_BIT |

           SC16IS7XX_EFR_AUTORTS_BIT;

+

   if (termios->c_iflag & IXON)

       flow |= SC16IS7XX_EFR_SWFLOW3_BIT;

   if (termios->c_iflag & IXOFF)

@@ -957,7 +971,7 @@ static int sc16is7xx_config_rs485(struct uart_port *port,

   port->rs485 = *rs485;

   one->config.flags |= SC16IS7XX_RECONF_RS485;

-   kthread_queue_work(&s->kworker, &one->reg_work);

+   queue_kthread_work(&s->kworker, &one->reg_work);

   return 0;

}

@@ -1030,7 +1044,7 @@ static void sc16is7xx_shutdown(struct uart_port *port)

   sc16is7xx_power(port, 0);

-   kthread_flush_worker(&s->kworker);

+   flush_kthread_worker(&s->kworker);

}

static const char *sc16is7xx_type(struct uart_port *port)

@@ -1097,7 +1111,8 @@ static const struct uart_ops sc16is7xx_ops = {

static int sc16is7xx_gpio_get(struct gpio_chip *chip, unsigned offset)

{

   unsigned int val;

-   struct sc16is7xx_port *s = gpiochip_get_data(chip);

+   struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,

+                       gpio);

   struct uart_port *port = &s->p[0].port;

   val = sc16is7xx_port_read(port, SC16IS7XX_IOSTATE_REG);

@@ -1107,7 +1122,8 @@ static int sc16is7xx_gpio_get(struct gpio_chip *chip, unsigned offset)

static void sc16is7xx_gpio_set(struct gpio_chip *chip, unsigned offset, int val)

{

-   struct sc16is7xx_port *s = gpiochip_get_data(chip);

+   struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,

+                       gpio);

   struct uart_port *port = &s->p[0].port;

   sc16is7xx_port_update(port, SC16IS7XX_IOSTATE_REG, BIT(offset),

@@ -1117,7 +1133,8 @@ static void sc16is7xx_gpio_set(struct gpio_chip *chip, unsigned offset, int val)

static int sc16is7xx_gpio_direction_input(struct gpio_chip *chip,

                    unsigned offset)

{

-   struct sc16is7xx_port *s = gpiochip_get_data(chip);

+   struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,

+                       gpio);

   struct uart_port *port = &s->p[0].port;

   sc16is7xx_port_update(port, SC16IS7XX_IODIR_REG, BIT(offset), 0);

@@ -1128,7 +1145,8 @@ static int sc16is7xx_gpio_direction_input(struct gpio_chip *chip,

static int sc16is7xx_gpio_direction_output(struct gpio_chip *chip,

                    unsigned offset, int val)

{

-   struct sc16is7xx_port *s = gpiochip_get_data(chip);

+   struct sc16is7xx_port *s = container_of(chip, struct sc16is7xx_port,

+                       gpio);

   struct uart_port *port = &s->p[0].port;

   u8 state = sc16is7xx_port_read(port, SC16IS7XX_IOSTATE_REG);

@@ -1150,7 +1168,7 @@ static int sc16is7xx_probe(struct device *dev,

{

   struct sched_param sched_param = { .sched_priority = MAX_RT_PRIO / 2 };

   unsigned long freq, *pfreq = dev_get_platdata(dev);

-   int i, ret;

+   int i, ret, gpioflags;

   struct sc16is7xx_port *s;

   if (IS_ERR(regmap))

@@ -1180,8 +1198,44 @@ static int sc16is7xx_probe(struct device *dev,

   s->devtype = devtype;

   dev_set_drvdata(dev, s);

-   kthread_init_worker(&s->kworker);

-   kthread_init_work(&s->irq_work, sc16is7xx_ist);

+   s->enable_gpio = of_get_named_gpio_flags(dev->of_node,

+                                           "enable-gpios", 0,

+                                           &gpioflags);

+   if (gpio_is_valid(s->enable_gpio)) {

+       unsigned int value;

+

+       if (gpioflags & OF_GPIO_ACTIVE_LOW)

+           s->enable_gpio_flags |= GPIO_ACTIVE_LOW;

+

+       ret = gpio_request(s->enable_gpio, "enable");

+       if (ret < 0) {

+           dev_err(dev, "failed to request GPIO#%u: %d\n",

+               s->enable_gpio, ret);

+           return ret;

+       }

+

+       value = (s->enable_gpio_flags & GPIO_ACTIVE_LOW) != 0;

+

+       ret = gpio_direction_output(s->enable_gpio, value);

+       if (ret < 0) {

+           dev_err(dev, "failed to setup GPIO%u: %d\n",

+               s->enable_gpio, ret);

+           goto free_gpio;

+       }

+   }

+

+   // turn on the chip

+   if (gpio_is_valid(s->enable_gpio)) {

+       if (s->enable_gpio_flags & GPIO_ACTIVE_LOW)

+           gpio_set_value(s->enable_gpio, 0);

+       else

+           gpio_set_value(s->enable_gpio, 1);

+   }

+

+   mdelay(30);

+

+   init_kthread_worker(&s->kworker);

+   init_kthread_work(&s->irq_work, sc16is7xx_ist);

   s->kworker_task = kthread_run(kthread_worker_fn, &s->kworker,

                "sc16is7xx");

   if (IS_ERR(s->kworker_task)) {

@@ -1194,7 +1248,7 @@ static int sc16is7xx_probe(struct device *dev,

   if (devtype->nr_gpio) {

       /* Setup GPIO cotroller */

       s->gpio.owner        = THIS_MODULE;

-       s->gpio.parent       = dev;

+       s->gpio.dev      = dev;

       s->gpio.label        = dev_name(dev);

       s->gpio.direction_input  = sc16is7xx_gpio_direction_input;

       s->gpio.get      = sc16is7xx_gpio_get;

@@ -1203,7 +1257,7 @@ static int sc16is7xx_probe(struct device *dev,

       s->gpio.base         = -1;

       s->gpio.ngpio        = devtype->nr_gpio;

       s->gpio.can_sleep    = 1;

-       ret = gpiochip_add_data(&s->gpio, s);

+       ret = gpiochip_add(&s->gpio);

       if (ret)

           goto out_thread;

   }

@@ -1238,8 +1292,8 @@ static int sc16is7xx_probe(struct device *dev,

                SC16IS7XX_EFCR_RXDISABLE_BIT |

                SC16IS7XX_EFCR_TXDISABLE_BIT);

       /* Initialize kthread work structs */

-       kthread_init_work(&s->p[i].tx_work, sc16is7xx_tx_proc);

-       kthread_init_work(&s->p[i].reg_work, sc16is7xx_reg_proc);

+       init_kthread_work(&s->p[i].tx_work, sc16is7xx_tx_proc);

+       init_kthread_work(&s->p[i].reg_work, sc16is7xx_reg_proc);

       /* Register port */

       uart_add_one_port(&sc16is7xx_uart, &s->p[i].port);

@@ -1286,6 +1340,10 @@ static int sc16is7xx_probe(struct device *dev,

   if (!IS_ERR(s->clk))

       clk_disable_unprepare(s->clk);

+free_gpio:

+   if (gpio_is_valid(s->enable_gpio))

+       gpio_free(s->enable_gpio);

+

   return ret;

}

@@ -1305,12 +1363,15 @@ static int sc16is7xx_remove(struct device *dev)

       sc16is7xx_power(&s->p[i].port, 0);

   }

-   kthread_flush_worker(&s->kworker);

+   flush_kthread_worker(&s->kworker);

   kthread_stop(s->kworker_task);

   if (!IS_ERR(s->clk))

       clk_disable_unprepare(s->clk);

+   if (gpio_is_valid(s->enable_gpio))

+       gpio_free(s->enable_gpio);

+

   return 0;

}