diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c index fff026f3d0bb..a2ee75dee070 100644 --- a/drivers/tty/serial/8250/8250_omap.c +++ b/drivers/tty/serial/8250/8250_omap.c @@ -33,6 +33,11 @@ #define UART_ERRATA_i202_MDR1_ACCESS (1 << 0) #define OMAP_UART_WER_HAS_TX_WAKEUP (1 << 1) #define OMAP_DMA_TX_KICK (1 << 2) +/* + * See Advisory 21 in AM437x errata SPRZ408B, updated April 2015. + * The same errata is applicable to AM335x and DRA7x processors too. + */ +#define UART_ERRATA_CLOCK_DISABLE (1 << 3) #define OMAP_UART_FCR_RX_TRIG 6 #define OMAP_UART_FCR_TX_TRIG 4 @@ -54,6 +59,12 @@ #define OMAP_UART_MVR_MAJ_SHIFT 8 #define OMAP_UART_MVR_MIN_MASK 0x3f +/* SYSC register bitmasks */ +#define OMAP_UART_SYSC_SOFTRESET (1 << 1) + +/* SYSS register bitmasks */ +#define OMAP_UART_SYSS_RESETDONE (1 << 0) + #define UART_TI752_TLR_TX 0 #define UART_TI752_TLR_RX 4 @@ -1062,13 +1073,15 @@ static int omap8250_no_handle_irq(struct uart_port *port) return 0; } -static const u8 am3352_habit = OMAP_DMA_TX_KICK; +static const u8 am3352_habit = OMAP_DMA_TX_KICK | UART_ERRATA_CLOCK_DISABLE; +static const u8 am4372_habit = UART_ERRATA_CLOCK_DISABLE; static const struct of_device_id omap8250_dt_ids[] = { { .compatible = "ti,omap2-uart" }, { .compatible = "ti,omap3-uart" }, { .compatible = "ti,omap4-uart" }, { .compatible = "ti,am3352-uart", .data = &am3352_habit, }, + { .compatible = "ti,am4372-uart", .data = &am4372_habit, }, {}, }; MODULE_DEVICE_TABLE(of, omap8250_dt_ids); @@ -1282,17 +1295,46 @@ static int omap8250_lost_context(struct uart_8250_port *up) { u32 val; - val = serial_in(up, UART_OMAP_MDR1); + val = serial_in(up, UART_OMAP_SCR); /* - * If we lose context, then MDR1 is set to its reset value which is - * UART_OMAP_MDR1_DISABLE. After set_termios() we set it either to 13x - * or 16x but never to disable again. + * If we lose context, then SCR is set to its reset value of zero. + * After set_termios() we set bit 3 of SCR (TX_EMPTY_CTL_IT) to 1, + * among other bits, to never set the register back to zero again. */ - if (val == UART_OMAP_MDR1_DISABLE) + if (!val) return 1; return 0; } +/* TODO: in future, this should happen via API in drivers/reset/ */ +static int omap8250_soft_reset(struct device *dev) +{ + struct omap8250_priv *priv = dev_get_drvdata(dev); + struct uart_8250_port *up = serial8250_get_port(priv->line); + int timeout = 100; + int sysc; + int syss; + + sysc = serial_in(up, UART_OMAP_SYSC); + + /* softreset the UART */ + sysc |= OMAP_UART_SYSC_SOFTRESET; + serial_out(up, UART_OMAP_SYSC, sysc); + + /* By experiments, 1us enough for reset complete on AM335x */ + do { + udelay(1); + syss = serial_in(up, UART_OMAP_SYSS); + } while (--timeout && !(syss & OMAP_UART_SYSS_RESETDONE)); + + if (!timeout) { + dev_err(dev, "timed out waiting for reset done\n"); + return -ETIMEDOUT; + } + + return 0; +} + static int omap8250_runtime_suspend(struct device *dev) { struct omap8250_priv *priv = dev_get_drvdata(dev); @@ -1310,6 +1352,17 @@ static int omap8250_runtime_suspend(struct device *dev) return -EBUSY; } + if (priv->habit & UART_ERRATA_CLOCK_DISABLE) { + int ret; + + ret = omap8250_soft_reset(dev); + if (ret) + return ret; + + /* Restore to UART mode after reset (for wakeup) */ + omap8250_update_mdr1(up, priv); + } + if (up->dma && up->dma->rxchan) omap_8250_rx_dma(up, UART_IIR_RX_TIMEOUT);