serial: Use -EAGAIN in getc and putc

U-Boot serial code already handles -EAGAIN value from getc and putc
callbacks. So change drivers code to return -EAGAIN when HW is busy instead
of doing its own busy loop and waiting until HW is ready.

Signed-off-by: Pali Rohár <pali@kernel.org>

diff --git a/drivers/serial/serial_arc.c b/drivers/serial/serial_arc.c
index b2d95bd..c2fc8a9 100644 (file)
--- a/drivers/serial/serial_arc.c
+++ b/drivers/serial/serial_arc.c
@@ -53,8 +53,8 @@ static int arc_serial_putc(struct udevice *dev, const char c)
        struct arc_serial_plat *plat = dev_get_plat(dev);
        struct arc_serial_regs *const regs = plat->reg;
 
-       while (!(readb(&regs->status) & UART_TXEMPTY))
-               ;
+       if (!(readb(&regs->status) & UART_TXEMPTY))
+               return -EAGAIN;
 
        writeb(c, &regs->data);
 
@@ -83,8 +83,8 @@ static int arc_serial_getc(struct udevice *dev)
        struct arc_serial_plat *plat = dev_get_plat(dev);
        struct arc_serial_regs *const regs = plat->reg;
 
-       while (!arc_serial_tstc(regs))
-               ;
+       if (!arc_serial_tstc(regs))
+               return -EAGAIN;
 
        /* Check for overflow errors */
        if (readb(&regs->status) & UART_OVERFLOW_ERR)

diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c
index 07941c2..51e66ab 100644 (file)
--- a/drivers/serial/serial_lpuart.c
+++ b/drivers/serial/serial_lpuart.c
@@ -168,23 +168,24 @@ static void _lpuart_serial_setbrg(struct udevice *dev,
 static int _lpuart_serial_getc(struct lpuart_serial_plat *plat)
 {
        struct lpuart_fsl *base = plat->reg;
-       while (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR)))
-               schedule();
+       if (!(__raw_readb(&base->us1) & (US1_RDRF | US1_OR)))
+               return -EAGAIN;
 
        barrier();
 
        return __raw_readb(&base->ud);
 }
 
-static void _lpuart_serial_putc(struct lpuart_serial_plat *plat,
+static int _lpuart_serial_putc(struct lpuart_serial_plat *plat,
                                const char c)
 {
        struct lpuart_fsl *base = plat->reg;
 
-       while (!(__raw_readb(&base->us1) & US1_TDRE))
-               schedule();
+       if (!(__raw_readb(&base->us1) & US1_TDRE))
+               return -EAGAIN;
 
        __raw_writeb(c, &base->ud);
+       return 0;
 }
 
 /* Test whether a character is in the RX buffer */
@@ -328,10 +329,9 @@ static int _lpuart32_serial_getc(struct lpuart_serial_plat *plat)
        u32 stat, val;
 
        lpuart_read32(plat->flags, &base->stat, &stat);
-       while ((stat & STAT_RDRF) == 0) {
+       if ((stat & STAT_RDRF) == 0) {
                lpuart_write32(plat->flags, &base->stat, STAT_FLAGS);
-               schedule();
-               lpuart_read32(plat->flags, &base->stat, &stat);
+               return -EAGAIN;
        }
 
        lpuart_read32(plat->flags, &base->data, &val);
@@ -343,22 +343,18 @@ static int _lpuart32_serial_getc(struct lpuart_serial_plat *plat)
        return val & 0x3ff;
 }
 
-static void _lpuart32_serial_putc(struct lpuart_serial_plat *plat,
+static int _lpuart32_serial_putc(struct lpuart_serial_plat *plat,
                                  const char c)
 {
        struct lpuart_fsl_reg32 *base = plat->reg;
        u32 stat;
 
-       while (true) {
-               lpuart_read32(plat->flags, &base->stat, &stat);
-
-               if ((stat & STAT_TDRE))
-                       break;
-
-               schedule();
-       }
+       lpuart_read32(plat->flags, &base->stat, &stat);
+       if (!(stat & STAT_TDRE))
+               return -EAGAIN;
 
        lpuart_write32(plat->flags, &base->data, c);
+       return 0;
 }
 
 /* Test whether a character is in the RX buffer */
@@ -453,11 +449,9 @@ static int lpuart_serial_putc(struct udevice *dev, const char c)
        struct lpuart_serial_plat *plat = dev_get_plat(dev);
 
        if (is_lpuart32(dev))
-               _lpuart32_serial_putc(plat, c);
-       else
-               _lpuart_serial_putc(plat, c);
+               return _lpuart32_serial_putc(plat, c);
 
-       return 0;
+       return _lpuart_serial_putc(plat, c);
 }
 
 static int lpuart_serial_pending(struct udevice *dev, bool input)

diff --git a/drivers/serial/serial_mpc8xx.c b/drivers/serial/serial_mpc8xx.c
index 808a40f..b8d6a81 100644 (file)
--- a/drivers/serial/serial_mpc8xx.c
+++ b/drivers/serial/serial_mpc8xx.c
@@ -178,14 +178,13 @@ static int serial_mpc8xx_putc(struct udevice *dev, const char c)
 
        rtx = (struct serialbuffer __iomem *)&cpmp->cp_dpmem[CPM_SERIAL_BASE];
 
-       /* Wait for last character to go. */
+       if (in_be16(&rtx->txbd.cbd_sc) & BD_SC_READY)
+               return -EAGAIN;
+
        out_8(&rtx->txbuf, c);
        out_be16(&rtx->txbd.cbd_datlen, 1);
        setbits_be16(&rtx->txbd.cbd_sc, BD_SC_READY);
 
-       while (in_be16(&rtx->txbd.cbd_sc) & BD_SC_READY)
-               schedule();
-
        return 0;
 }
 
@@ -199,9 +198,8 @@ static int serial_mpc8xx_getc(struct udevice *dev)
 
        rtx = (struct serialbuffer __iomem *)&cpmp->cp_dpmem[CPM_SERIAL_BASE];
 
-       /* Wait for character to show up. */
-       while (in_be16(&rtx->rxbd.cbd_sc) & BD_SC_EMPTY)
-               schedule();
+       if (in_be16(&rtx->rxbd.cbd_sc) & BD_SC_EMPTY)
+               return -EAGAIN;
 
        /* the characters are read one by one,
         * use the rxindex to know the next char to deliver

diff --git a/drivers/serial/serial_mvebu_a3700.c b/drivers/serial/serial_mvebu_a3700.c
index 0fcd7e8..b2017c6 100644 (file)
--- a/drivers/serial/serial_mvebu_a3700.c
+++ b/drivers/serial/serial_mvebu_a3700.c
@@ -40,8 +40,8 @@ static int mvebu_serial_putc(struct udevice *dev, const char ch)
        struct mvebu_plat *plat = dev_get_plat(dev);
        void __iomem *base = plat->base;
 
-       while (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL)
-               ;
+       if (readl(base + UART_STATUS_REG) & UART_STATUS_TXFIFO_FULL)
+               return -EAGAIN;
 
        writel(ch, base + UART_TX_REG);
 
@@ -53,8 +53,8 @@ static int mvebu_serial_getc(struct udevice *dev)
        struct mvebu_plat *plat = dev_get_plat(dev);
        void __iomem *base = plat->base;
 
-       while (!(readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY))
-               ;
+       if (!(readl(base + UART_STATUS_REG) & UART_STATUS_RX_RDY))
+               return -EAGAIN;
 
        return readl(base + UART_RX_REG) & 0xff;
 }