sc16is7xx: use kworker for RS-485 configuration

RS-485 configuration is also done under the spinlock
so no blocking I/O allowed.

Signed-off-by: Jakub Kicinski <kubakici@wp.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 29 insertions, 12 deletions

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 86a679a5870b..9e6576004a42 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -303,6 +303,7 @@ struct sc16is7xx_devtype {
 
 #define SC16IS7XX_RECONF_MD             (1 << 0)
 #define SC16IS7XX_RECONF_IER            (1 << 1)
+#define SC16IS7XX_RECONF_RS485          (1 << 2)
 
 struct sc16is7xx_one_config {
         unsigned int                    flags;
@@ -668,6 +669,26 @@ static void sc16is7xx_tx_proc(struct kthread_work *ws)
         sc16is7xx_handle_tx(port);
 }
 
+static void sc16is7xx_reconf_rs485(struct uart_port *port)
+{
+        const u32 mask = SC16IS7XX_EFCR_AUTO_RS485_BIT |
+                         SC16IS7XX_EFCR_RTS_INVERT_BIT;
+        u32 efcr = 0;
+        struct serial_rs485 *rs485 = &port->rs485;
+        unsigned long irqflags;
+
+        spin_lock_irqsave(&port->lock, irqflags);
+        if (rs485->flags & SER_RS485_ENABLED) {
+                efcr |= SC16IS7XX_EFCR_AUTO_RS485_BIT;
+
+                if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
+                        efcr |= SC16IS7XX_EFCR_RTS_INVERT_BIT;
+        }
+        spin_unlock_irqrestore(&port->lock, irqflags);
+
+        sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG, mask, efcr);
+}
+
 static void sc16is7xx_reg_proc(struct kthread_work *ws)
 {
         struct sc16is7xx_one *one = to_sc16is7xx_one(ws, reg_work);
@@ -688,6 +709,9 @@ static void sc16is7xx_reg_proc(struct kthread_work *ws)
         if (config.flags & SC16IS7XX_RECONF_IER)
                 sc16is7xx_port_update(&one->port, SC16IS7XX_IER_REG,
                                       config.ier_clear, 0);
+
+        if (config.flags & SC16IS7XX_RECONF_RS485)
+                sc16is7xx_reconf_rs485(&one->port);
 }
 
 static void sc16is7xx_ier_clear(struct uart_port *port, u8 bit)
@@ -845,9 +869,8 @@ static void sc16is7xx_set_termios(struct uart_port *port,
 static int sc16is7xx_config_rs485(struct uart_port *port,
                                   struct serial_rs485 *rs485)
 {
-        const u32 mask = SC16IS7XX_EFCR_AUTO_RS485_BIT |
-                         SC16IS7XX_EFCR_RTS_INVERT_BIT;
-        u32 efcr = 0;
+        struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+        struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
         if (rs485->flags & SER_RS485_ENABLED) {
                 bool rts_during_rx, rts_during_tx;
@@ -855,13 +878,7 @@ static int sc16is7xx_config_rs485(struct uart_port *port,
                 rts_during_rx = rs485->flags & SER_RS485_RTS_AFTER_SEND;
                 rts_during_tx = rs485->flags & SER_RS485_RTS_ON_SEND;
 
-                efcr |= SC16IS7XX_EFCR_AUTO_RS485_BIT;
-
-                if (!rts_during_rx && rts_during_tx)
-                        /* default */;
-                else if (rts_during_rx && !rts_during_tx)
-                        efcr |= SC16IS7XX_EFCR_RTS_INVERT_BIT;
-                else
+                if (rts_during_rx == rts_during_tx)
                         dev_err(port->dev,
                                 "unsupported RTS signalling on_send:%d after_send:%d - exactly one of RS485 RTS flags should be set\n",
                                 rts_during_tx, rts_during_rx);
@@ -875,9 +892,9 @@ static int sc16is7xx_config_rs485(struct uart_port *port,
                         return -EINVAL;
         }
 
-        sc16is7xx_port_update(port, SC16IS7XX_EFCR_REG, mask, efcr);
-
         port->rs485 = *rs485;
+        one->config.flags |= SC16IS7XX_RECONF_RS485;
+        queue_kthread_work(&s->kworker, &one->reg_work);
 
         return 0;
 }