tty: Blackin CTS/RTS

Both software emulated and hardware based CTS and RTS are enabled in
serial driver.

The CTS RTS PIN connection on BF548 UART port is defined as a modem
device not as a host device.  In order to test it under Linux, please
nake a cross UART cable to exchange CTS and RTS signal.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 117 insertions, 52 deletions

diff --git a/drivers/serial/bfin_5xx.c b/drivers/serial/bfin_5xx.c
index fbbddb9e73f6..18ba812a4f84 100644
--- a/drivers/serial/bfin_5xx.c
+++ b/drivers/serial/bfin_5xx.c
@@ -72,6 +72,63 @@ static void bfin_serial_tx_chars(struct bfin_serial_port *uart);
 
 static void bfin_serial_reset_irda(struct uart_port *port);
 
+#if defined(CONFIG_SERIAL_BFIN_CTSRTS) || \
+        defined(CONFIG_SERIAL_BFIN_HARD_CTSRTS)
+static unsigned int bfin_serial_get_mctrl(struct uart_port *port)
+{
+        struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
+        if (uart->cts_pin < 0)
+                return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+
+        /* CTS PIN is negative assertive. */
+        if (UART_GET_CTS(uart))
+                return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+        else
+                return TIOCM_DSR | TIOCM_CAR;
+}
+
+static void bfin_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+        struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
+        if (uart->rts_pin < 0)
+                return;
+
+        /* RTS PIN is negative assertive. */
+        if (mctrl & TIOCM_RTS)
+                UART_ENABLE_RTS(uart);
+        else
+                UART_DISABLE_RTS(uart);
+}
+
+/*
+ * Handle any change of modem status signal.
+ */
+static irqreturn_t bfin_serial_mctrl_cts_int(int irq, void *dev_id)
+{
+        struct bfin_serial_port *uart = dev_id;
+        unsigned int status;
+
+        status = bfin_serial_get_mctrl(&uart->port);
+        uart_handle_cts_change(&uart->port, status & TIOCM_CTS);
+#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS
+        uart->scts = 1;
+        UART_CLEAR_SCTS(uart);
+        UART_CLEAR_IER(uart, EDSSI);
+#endif
+
+        return IRQ_HANDLED;
+}
+#else
+static unsigned int bfin_serial_get_mctrl(struct uart_port *port)
+{
+        return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+}
+
+static void bfin_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+}
+#endif
+
 /*
  * interrupts are disabled on entry
  */
@@ -108,6 +165,13 @@ static void bfin_serial_start_tx(struct uart_port *port)
         struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
         struct tty_struct *tty = uart->port.info->port.tty;
 
+#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS
+        if (uart->scts && (!bfin_serial_get_mctrl(&uart->port)&TIOCM_CTS)) {
+                uart->scts = 0;
+                uart_handle_cts_change(&uart->port, uart->scts);
+        }
+#endif
+
         /*
          * To avoid losting RX interrupt, we reset IR function
          * before sending data.
@@ -303,6 +367,12 @@ static irqreturn_t bfin_serial_tx_int(int irq, void *dev_id)
 {
         struct bfin_serial_port *uart = dev_id;
 
+#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS
+        if (uart->scts && (!bfin_serial_get_mctrl(&uart->port)&TIOCM_CTS)) {
+                uart->scts = 0;
+                uart_handle_cts_change(&uart->port, uart->scts);
+        }
+#endif
         spin_lock(&uart->port.lock);
         if (UART_GET_LSR(uart) & THRE)
                 bfin_serial_tx_chars(uart);
@@ -433,6 +503,13 @@ static irqreturn_t bfin_serial_dma_tx_int(int irq, void *dev_id)
         struct bfin_serial_port *uart = dev_id;
         struct circ_buf *xmit = &uart->port.info->xmit;
 
+#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS
+        if (uart->scts && (!bfin_serial_get_mctrl(&uart->port)&TIOCM_CTS)) {
+                uart->scts = 0;
+                uart_handle_cts_change(&uart->port, uart->scts);
+        }
+#endif
+
         spin_lock(&uart->port.lock);
         if (!(get_dma_curr_irqstat(uart->tx_dma_channel)&DMA_RUN)) {
                 disable_dma(uart->tx_dma_channel);
@@ -481,53 +558,6 @@ static unsigned int bfin_serial_tx_empty(struct uart_port *port)
                 return 0;
 }
 
-static unsigned int bfin_serial_get_mctrl(struct uart_port *port)
-{
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
-        struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
-        if (uart->cts_pin < 0)
-                return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
-
-        if (UART_GET_CTS(uart))
-                return TIOCM_DSR | TIOCM_CAR;
-        else
-#endif
-                return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
-}
-
-static void bfin_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
-{
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
-        struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
-        if (uart->rts_pin < 0)
-                return;
-
-        if (mctrl & TIOCM_RTS)
-                UART_CLEAR_RTS(uart);
-        else
-                UART_SET_RTS(uart);
-#endif
-}
-
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
-/*
- * Handle any change of modem status signal.
- */
-static irqreturn_t bfin_serial_mctrl_cts_int(int irq, void *dev_id)
-{
-        struct bfin_serial_port *uart = dev_id;
-        unsigned int status;
-
-        status = bfin_serial_get_mctrl(&uart->port);
-        uart_handle_cts_change(&uart->port, status & TIOCM_CTS);
-
-        return IRQ_HANDLED;
-}
-#endif
-
-/*
- * Interrupts are always disabled.
- */
 static void bfin_serial_break_ctl(struct uart_port *port, int break_state)
 {
         struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
@@ -660,6 +690,28 @@ static int bfin_serial_startup(struct uart_port *port)
                 gpio_direction_output(uart->rts_pin, 0);
         }
 #endif
+#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS
+        if (request_irq(uart->status_irq,
+                bfin_serial_mctrl_cts_int,
+                IRQF_DISABLED, "BFIN_UART_MODEM_STATUS", uart)) {
+                pr_info("Unable to attach BlackFin UART Modem \
+                        Status interrupt.\n");
+        }
+
+        if (uart->cts_pin >= 0) {
+                gpio_request(uart->cts_pin, DRIVER_NAME);
+                gpio_direction_output(uart->cts_pin, 1);
+        }
+        if (uart->rts_pin >= 0) {
+                gpio_request(uart->rts_pin, DRIVER_NAME);
+                gpio_direction_output(uart->rts_pin, 0);
+        }
+
+        /* CTS RTS PINs are negative assertive. */
+        UART_PUT_MCR(uart, ACTS);
+        UART_SET_IER(uart, EDSSI);
+#endif
+
         UART_SET_IER(uart, ERBFI);
         return 0;
 }
@@ -694,12 +746,20 @@ static void bfin_serial_shutdown(struct uart_port *port)
         free_irq(uart->port.irq+1, uart);
 #endif
 
-# ifdef CONFIG_SERIAL_BFIN_CTSRTS
+#ifdef CONFIG_SERIAL_BFIN_CTSRTS
         if (uart->cts_pin >= 0)
                 free_irq(gpio_to_irq(uart->cts_pin), uart);
         if (uart->rts_pin >= 0)
                 gpio_free(uart->rts_pin);
-# endif
+#endif
+#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS
+        if (uart->cts_pin >= 0)
+                gpio_free(uart->cts_pin);
+        if (uart->rts_pin >= 0)
+                gpio_free(uart->rts_pin);
+        if (UART_GET_IER(uart) && EDSSI)
+                free_irq(uart->status_irq, uart);
+#endif
 }
 
 static void
@@ -1009,6 +1069,8 @@ static void __init bfin_serial_init_ports(void)
                         bfin_serial_resource[i].uart_base_addr;
                 bfin_serial_ports[i].port.irq       =
                         bfin_serial_resource[i].uart_irq;
+                bfin_serial_ports[i].status_irq     =
+                        bfin_serial_resource[i].uart_status_irq;
                 bfin_serial_ports[i].port.flags     = UPF_BOOT_AUTOCONF;
 #ifdef CONFIG_SERIAL_BFIN_DMA
                 bfin_serial_ports[i].tx_done        = 1;
@@ -1019,7 +1081,8 @@ static void __init bfin_serial_init_ports(void)
                         bfin_serial_resource[i].uart_rx_dma_channel;
                 init_timer(&(bfin_serial_ports[i].rx_dma_timer));
 #endif
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
+#if defined(CONFIG_SERIAL_BFIN_CTSRTS) || \
+        defined(CONFIG_SERIAL_BFIN_HARD_CTSRTS)
                 bfin_serial_ports[i].cts_pin        =
                         bfin_serial_resource[i].uart_cts_pin;
                 bfin_serial_ports[i].rts_pin        =
@@ -1082,7 +1145,8 @@ bfin_serial_console_setup(struct console *co, char *options)
         int baud = 57600;
         int bits = 8;
         int parity = 'n';
-# ifdef CONFIG_SERIAL_BFIN_CTSRTS
+# if defined(CONFIG_SERIAL_BFIN_CTSRTS) || \
+        defined(CONFIG_SERIAL_BFIN_HARD_CTSRTS)
         int flow = 'r';
 # else
         int flow = 'n';
@@ -1279,7 +1343,8 @@ static int bfin_serial_remove(struct platform_device *dev)
                         continue;
                 uart_remove_one_port(&bfin_serial_reg, &bfin_serial_ports[i].port);
                 bfin_serial_ports[i].port.dev = NULL;
-#ifdef CONFIG_SERIAL_BFIN_CTSRTS
+#if defined(CONFIG_SERIAL_BFIN_CTSRTS) || \
+        defined(CONFIG_SERIAL_BFIN_HARD_CTSRTS)
                 gpio_free(bfin_serial_ports[i].cts_pin);
                 gpio_free(bfin_serial_ports[i].rts_pin);
 #endif