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 <p...@kernel.org> --- Changes in v2: * Fix serial_lpuart.c code after Tom's review * Add serial_mpc8xx.c change To prevent merge conflicts, please apply this patch *after* this: http://patchwork.ozlabs.org/project/uboot/patch/20221210232744.15600-1-p...@kernel.org/ --- drivers/serial/serial_arc.c | 8 +++---- drivers/serial/serial_lpuart.c | 36 ++++++++++++----------------- drivers/serial/serial_mpc8xx.c | 12 ++++------ drivers/serial/serial_mvebu_a3700.c | 8 +++---- 4 files changed, 28 insertions(+), 36 deletions(-) diff --git a/drivers/serial/serial_arc.c b/drivers/serial/serial_arc.c index b2d95bdbe18d..c2fc8a901e25 100644 --- 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(®s->status) & UART_TXEMPTY)) - ; + if (!(readb(®s->status) & UART_TXEMPTY)) + return -EAGAIN; writeb(c, ®s->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(®s->status) & UART_OVERFLOW_ERR) diff --git a/drivers/serial/serial_lpuart.c b/drivers/serial/serial_lpuart.c index 07941c29ed74..51e66abdbc15 100644 --- 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 808a40f503ea..b8d6a81b650f 100644 --- 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 0fcd7e88acee..b2017c645565 100644 --- 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; } -- 2.20.1
