serial: stm32: push DMA RX data before suspending

[linux-2.6-microblaze.git] / drivers / tty / serial / stm32-usart.c

diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index 4b5b074..3244e7f 100644 (file)
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -210,11 +210,12 @@ static unsigned long stm32_usart_get_char_pio(struct uart_port *port)
        return c;
 }
 
-static void stm32_usart_receive_chars_pio(struct uart_port *port)
+static unsigned int stm32_usart_receive_chars_pio(struct uart_port *port)
 {
        struct stm32_port *stm32_port = to_stm32_port(port);
        const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
        unsigned long c;
+       unsigned int size = 0;
        u32 sr;
        char flag;
 
@@ -239,6 +240,7 @@ static void stm32_usart_receive_chars_pio(struct uart_port *port)
 
                c = stm32_usart_get_char_pio(port);
                port->icount.rx++;
+               size++;
                if (sr & USART_SR_ERR_MASK) {
                        if (sr & USART_SR_ORE) {
                                port->icount.overrun++;
@@ -271,6 +273,8 @@ static void stm32_usart_receive_chars_pio(struct uart_port *port)
                        continue;
                uart_insert_char(port, sr, USART_SR_ORE, c, flag);
        }
+
+       return size;
 }
 
 static void stm32_usart_push_buffer_dma(struct uart_port *port, unsigned int dma_size)
@@ -300,50 +304,48 @@ static void stm32_usart_push_buffer_dma(struct uart_port *port, unsigned int dma
                stm32_port->last_res = RX_BUF_L;
 }
 
-static void stm32_usart_receive_chars_dma(struct uart_port *port)
+static unsigned int stm32_usart_receive_chars_dma(struct uart_port *port)
 {
        struct stm32_port *stm32_port = to_stm32_port(port);
-       unsigned int dma_size;
+       unsigned int dma_size, size = 0;
 
        /* DMA buffer is configured in cyclic mode and handles the rollback of the buffer. */
        if (stm32_port->rx_dma_state.residue > stm32_port->last_res) {
                /* Conditional first part: from last_res to end of DMA buffer */
                dma_size = stm32_port->last_res;
                stm32_usart_push_buffer_dma(port, dma_size);
+               size = dma_size;
        }
 
        dma_size = stm32_port->last_res - stm32_port->rx_dma_state.residue;
        stm32_usart_push_buffer_dma(port, dma_size);
+       size += dma_size;
+
+       return size;
 }
 
-static void stm32_usart_receive_chars(struct uart_port *port, bool irqflag)
+static unsigned int stm32_usart_receive_chars(struct uart_port *port, bool force_dma_flush)
 {
-       struct tty_port *tport = &port->state->port;
        struct stm32_port *stm32_port = to_stm32_port(port);
        const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
        enum dma_status rx_dma_status;
-       unsigned long flags;
        u32 sr;
+       unsigned int size = 0;
 
-       if (irqflag)
-               spin_lock_irqsave(&port->lock, flags);
-       else
-               spin_lock(&port->lock);
-
-       if (stm32_usart_rx_dma_enabled(port)) {
+       if (stm32_usart_rx_dma_enabled(port) || force_dma_flush) {
                rx_dma_status = dmaengine_tx_status(stm32_port->rx_ch,
                                                    stm32_port->rx_ch->cookie,
                                                    &stm32_port->rx_dma_state);
                if (rx_dma_status == DMA_IN_PROGRESS) {
                        /* Empty DMA buffer */
-                       stm32_usart_receive_chars_dma(port);
+                       size = stm32_usart_receive_chars_dma(port);
                        sr = readl_relaxed(port->membase + ofs->isr);
                        if (sr & USART_SR_ERR_MASK) {
                                /* Disable DMA request line */
                                stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
 
                                /* Switch to PIO mode to handle the errors */
-                               stm32_usart_receive_chars_pio(port);
+                               size += stm32_usart_receive_chars_pio(port);
 
                                /* Switch back to DMA mode */
                                stm32_usart_set_bits(port, ofs->cr3, USART_CR3_DMAR);
@@ -354,18 +356,13 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool irqflag)
                        stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
                        /* Fall back to interrupt mode */
                        dev_dbg(port->dev, "DMA error, fallback to irq mode\n");
-                       stm32_usart_receive_chars_pio(port);
+                       size = stm32_usart_receive_chars_pio(port);
                }
        } else {
-               stm32_usart_receive_chars_pio(port);
+               size = stm32_usart_receive_chars_pio(port);
        }
 
-       if (irqflag)
-               uart_unlock_and_check_sysrq_irqrestore(port, irqflag);
-       else
-               uart_unlock_and_check_sysrq(port);
-
-       tty_flip_buffer_push(tport);
+       return size;
 }
 
 static void stm32_usart_tx_dma_complete(void *arg)
@@ -403,8 +400,15 @@ static void stm32_usart_tx_interrupt_enable(struct uart_port *port)
 static void stm32_usart_rx_dma_complete(void *arg)
 {
        struct uart_port *port = arg;
+       struct tty_port *tport = &port->state->port;
+       unsigned int size;
+       unsigned long flags;
 
-       stm32_usart_receive_chars(port, true);
+       spin_lock_irqsave(&port->lock, flags);
+       size = stm32_usart_receive_chars(port, false);
+       uart_unlock_and_check_sysrq_irqrestore(port, flags);
+       if (size)
+               tty_flip_buffer_push(tport);
 }
 
 static void stm32_usart_tx_interrupt_disable(struct uart_port *port)
@@ -557,6 +561,7 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
        struct stm32_port *stm32_port = to_stm32_port(port);
        const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
        u32 sr;
+       unsigned int size;
 
        sr = readl_relaxed(port->membase + ofs->isr);
 
@@ -580,7 +585,11 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
        if (!stm32_port->throttled) {
                if (((sr & USART_SR_RXNE) && !stm32_usart_rx_dma_enabled(port)) ||
                    ((sr & USART_SR_ERR_MASK) && stm32_usart_rx_dma_enabled(port))) {
-                       stm32_usart_receive_chars(port, false);
+                       spin_lock(&port->lock);
+                       size = stm32_usart_receive_chars(port, false);
+                       uart_unlock_and_check_sysrq(port);
+                       if (size)
+                               tty_flip_buffer_push(tport);
                }
        }
 
@@ -599,11 +608,19 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)
 static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr)
 {
        struct uart_port *port = ptr;
+       struct tty_port *tport = &port->state->port;
        struct stm32_port *stm32_port = to_stm32_port(port);
+       unsigned int size;
+       unsigned long flags;
 
        /* Receiver timeout irq for DMA RX */
-       if (!stm32_port->throttled)
-               stm32_usart_receive_chars(port, false);
+       if (!stm32_port->throttled) {
+               spin_lock_irqsave(&port->lock, flags);
+               size = stm32_usart_receive_chars(port, false);
+               uart_unlock_and_check_sysrq_irqrestore(port, flags);
+               if (size)
+                       tty_flip_buffer_push(tport);
+       }
 
        return IRQ_HANDLED;
 }
@@ -1678,6 +1695,8 @@ static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port,
        const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
        struct tty_port *tport = &port->state->port;
        int ret;
+       unsigned int size;
+       unsigned long flags;
 
        if (!stm32_port->wakeup_src || !tty_port_initialized(tport))
                return 0;
@@ -1696,8 +1715,15 @@ static int __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port,
                 * low-power mode.
                 */
                if (stm32_port->rx_ch) {
+                       spin_lock_irqsave(&port->lock, flags);
+                       /* Avoid race with RX IRQ when DMAR is cleared */
                        stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_DMAR);
-                       dmaengine_terminate_sync(stm32_port->rx_ch);
+                       /* Poll data from DMA RX buffer if any */
+                       size = stm32_usart_receive_chars(port, true);
+                       dmaengine_terminate_async(stm32_port->rx_ch);
+                       uart_unlock_and_check_sysrq_irqrestore(port, flags);
+                       if (size)
+                               tty_flip_buffer_push(tport);
                }
 
                /* Poll data from RX FIFO if any */