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serial: 8250_dw: Use 64-bit access for OCTEON.

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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 <david.daney@cavium.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
David Daney 2014-11-14 17:26:19 +03:00 committed by Greg Kroah-Hartman
parent 93d94b37fd
commit bca2092d78
1 changed files with 41 additions and 14 deletions
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55
drivers/tty/serial/8250/8250_dw.c
View file

@ -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;