From bca2092d78970df3959462d2aae1941e6b24ebdf Mon Sep 17 00:00:00 2001 From: David Daney Date: Fri, 14 Nov 2014 17:26:19 +0300 Subject: [PATCH] serial: 8250_dw: Use 64-bit access for OCTEON. Although the existing code appears to work on most hardware, the hardware designers tell us that 8-bit access to the registers is not guaranteed to be reliable. Also the OCTEON simulation environments prohibit 8-bit accesses. For these reasons, we use __raw_readq/__raw_writeq for OCTEON. This code is protected with #ifdef CONFIG_64BIT so it still builds under configurations lacking readq/writeq. We can get rid of the #ifdef __BIG_ENDIAN, as under 64-bit accesses, OCTEON is byte order invariant. Signed-off-by: David Daney Signed-off-by: Aleksey Makarov Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_dw.c | 55 +++++++++++++++++++++++++++++---------- 1 file changed, 41 insertions(+), 14 deletions(-) diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c index 18ff532..f4fd362 100644 --- a/drivers/tty/serial/8250/8250_dw.c +++ b/drivers/tty/serial/8250/8250_dw.c @@ -122,13 +122,44 @@ static unsigned int dw8250_serial_in(struct uart_port *p, int offset) return dw8250_modify_msr(p, offset, value); } -/* Read Back (rb) version to ensure register access ording. */ -static void dw8250_serial_out_rb(struct uart_port *p, int offset, int value) +#ifdef CONFIG_64BIT +static unsigned int dw8250_serial_inq(struct uart_port *p, int offset) { - dw8250_serial_out(p, offset, value); - dw8250_serial_in(p, UART_LCR); + unsigned int value; + + value = (u8)__raw_readq(p->membase + (offset << p->regshift)); + + return dw8250_modify_msr(p, offset, value); } +static void dw8250_serial_outq(struct uart_port *p, int offset, int value) +{ + struct dw8250_data *d = p->private_data; + + if (offset == UART_MCR) + d->last_mcr = value; + + value &= 0xff; + __raw_writeq(value, p->membase + (offset << p->regshift)); + /* Read back to ensure register write ordering. */ + __raw_readq(p->membase + (UART_LCR << p->regshift)); + + /* Make sure LCR write wasn't ignored */ + if (offset == UART_LCR) { + int tries = 1000; + while (tries--) { + unsigned int lcr = p->serial_in(p, UART_LCR); + if ((value & ~UART_LCR_SPAR) == (lcr & ~UART_LCR_SPAR)) + return; + dw8250_force_idle(p); + __raw_writeq(value & 0xff, + p->membase + (UART_LCR << p->regshift)); + } + dev_err(p->dev, "Couldn't set LCR to %d\n", value); + } +} +#endif /* CONFIG_64BIT */ + static void dw8250_serial_out32(struct uart_port *p, int offset, int value) { struct dw8250_data *d = p->private_data; @@ -260,21 +291,17 @@ static int dw8250_probe_of(struct uart_port *p, bool has_ucv = true; int id; +#ifdef CONFIG_64BIT if (of_device_is_compatible(np, "cavium,octeon-3860-uart")) { -#ifdef __BIG_ENDIAN - /* - * Low order bits of these 64-bit registers, when - * accessed as a byte, are 7 bytes further down in the - * address space in big endian mode. - */ - p->membase += 7; -#endif - p->serial_out = dw8250_serial_out_rb; + p->serial_in = dw8250_serial_inq; + p->serial_out = dw8250_serial_outq; p->flags = UPF_SKIP_TEST | UPF_SHARE_IRQ | UPF_FIXED_TYPE; p->type = PORT_OCTEON; data->usr_reg = 0x27; has_ucv = false; - } else if (!of_property_read_u32(np, "reg-io-width", &val)) { + } else +#endif + if (!of_property_read_u32(np, "reg-io-width", &val)) { switch (val) { case 1: break; -- 2.7.4