diff options
Diffstat (limited to 'drivers/tty/serial/amba-pl011.c')
| -rw-r--r-- | drivers/tty/serial/amba-pl011.c | 70 |
1 files changed, 61 insertions, 9 deletions
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index d4171d71a258..8789ea423ccf 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -97,6 +97,7 @@ struct vendor_data { unsigned int fr_dsr; unsigned int fr_cts; unsigned int fr_ri; + unsigned int inv_fr; bool access_32b; bool oversampling; bool dma_threshold; @@ -141,6 +142,30 @@ static struct vendor_data vendor_sbsa = { .fixed_options = true, }; +/* + * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as + * occasionally getting stuck as 1. To avoid the potential for a hang, check + * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART + * implementations, so only do so if an affected platform is detected in + * parse_spcr(). + */ +static bool qdf2400_e44_present = false; + +static struct vendor_data vendor_qdt_qdf2400_e44 = { + .reg_offset = pl011_std_offsets, + .fr_busy = UART011_FR_TXFE, + .fr_dsr = UART01x_FR_DSR, + .fr_cts = UART01x_FR_CTS, + .fr_ri = UART011_FR_RI, + .inv_fr = UART011_FR_TXFE, + .access_32b = true, + .oversampling = false, + .dma_threshold = false, + .cts_event_workaround = false, + .always_enabled = true, + .fixed_options = true, +}; + static u16 pl011_st_offsets[REG_ARRAY_SIZE] = { [REG_DR] = UART01x_DR, [REG_ST_DMAWM] = ST_UART011_DMAWM, @@ -1518,7 +1543,10 @@ static unsigned int pl011_tx_empty(struct uart_port *port) { struct uart_amba_port *uap = container_of(port, struct uart_amba_port, port); - unsigned int status = pl011_read(uap, REG_FR); + + /* Allow feature register bits to be inverted to work around errata */ + unsigned int status = pl011_read(uap, REG_FR) ^ uap->vendor->inv_fr; + return status & (uap->vendor->fr_busy | UART01x_FR_TXFF) ? 0 : TIOCSER_TEMT; } @@ -2114,7 +2142,7 @@ static int pl011_verify_port(struct uart_port *port, struct serial_struct *ser) return ret; } -static struct uart_ops amba_pl011_pops = { +static const struct uart_ops amba_pl011_pops = { .tx_empty = pl011_tx_empty, .set_mctrl = pl011_set_mctrl, .get_mctrl = pl011_get_mctrl, @@ -2215,10 +2243,12 @@ pl011_console_write(struct console *co, const char *s, unsigned int count) uart_console_write(&uap->port, s, count, pl011_console_putchar); /* - * Finally, wait for transmitter to become empty - * and restore the TCR + * Finally, wait for transmitter to become empty and restore the + * TCR. Allow feature register bits to be inverted to work around + * errata. */ - while (pl011_read(uap, REG_FR) & uap->vendor->fr_busy) + while ((pl011_read(uap, REG_FR) ^ uap->vendor->inv_fr) + & uap->vendor->fr_busy) cpu_relax(); if (!uap->vendor->always_enabled) pl011_write(old_cr, uap, REG_CR); @@ -2340,8 +2370,12 @@ static int __init pl011_console_match(struct console *co, char *name, int idx, resource_size_t addr; int i; - if (strcmp(name, "pl011") != 0) + if (strcmp(name, "qdf2400_e44") == 0) { + pr_info_once("UART: Working around QDF2400 SoC erratum 44"); + qdf2400_e44_present = true; + } else if (strcmp(name, "pl011") != 0 || strcmp(name, "ttyAMA") != 0) { return -ENODEV; + } if (uart_parse_earlycon(options, &iotype, &addr, &options)) return -ENODEV; @@ -2376,13 +2410,29 @@ static struct console amba_console = { .device = uart_console_device, .setup = pl011_console_setup, .match = pl011_console_match, - .flags = CON_PRINTBUFFER, + .flags = CON_PRINTBUFFER | CON_ANYTIME, .index = -1, .data = &amba_reg, }; #define AMBA_CONSOLE (&amba_console) +static void qdf2400_e44_putc(struct uart_port *port, int c) +{ + while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF) + cpu_relax(); + writel(c, port->membase + UART01x_DR); + while (!(readl(port->membase + UART01x_FR) & UART011_FR_TXFE)) + cpu_relax(); +} + +static void qdf2400_e44_early_write(struct console *con, const char *s, unsigned n) +{ + struct earlycon_device *dev = con->data; + + uart_console_write(&dev->port, s, n, qdf2400_e44_putc); +} + static void pl011_putc(struct uart_port *port, int c) { while (readl(port->membase + UART01x_FR) & UART01x_FR_TXFF) @@ -2408,7 +2458,8 @@ static int __init pl011_early_console_setup(struct earlycon_device *device, if (!device->port.membase) return -ENODEV; - device->con->write = pl011_early_write; + device->con->write = qdf2400_e44_present ? + qdf2400_e44_early_write : pl011_early_write; return 0; } OF_EARLYCON_DECLARE(pl011, "arm,pl011", pl011_early_console_setup); @@ -2645,7 +2696,8 @@ static int sbsa_uart_probe(struct platform_device *pdev) uap->port.irq = ret; uap->reg_offset = vendor_sbsa.reg_offset; - uap->vendor = &vendor_sbsa; + uap->vendor = qdf2400_e44_present ? + &vendor_qdt_qdf2400_e44 : &vendor_sbsa; uap->fifosize = 32; uap->port.iotype = vendor_sbsa.access_32b ? UPIO_MEM32 : UPIO_MEM; uap->port.ops = &sbsa_uart_pops; |