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drivers: PL011: allow avoiding UART enabling/disabling 

The SBSA UART should not be enabled or disabled (it is always on),
and consequently the spec lacks the UART_CR register.
Add a vendor specific property to skip disabling or enabling of the
UART. This will be used later by the SBSA UART support.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Mark Langsdorf <mlangsdo@redhat.com>
Tested-by: Naresh Bhat <nbhat@cavium.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Andre Przywara 2015-05-21 17:26:21 +01:00 committed by Greg Kroah-Hartman
parent 9c4ef4b030
commit 71eec4836b
1 changed files with 12 additions and 6 deletions
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18
drivers/tty/serial/amba-pl011.c
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@ -78,6 +78,7 @@ struct vendor_data {
bool oversampling;
bool dma_threshold;
bool cts_event_workaround;
bool always_enabled;
unsigned int (*get_fifosize)(struct amba_device *dev);
};
@ -94,6 +95,7 @@ static struct vendor_data vendor_arm = {
.oversampling = false,
.dma_threshold = false,
.cts_event_workaround = false,
.always_enabled = false,
.get_fifosize = get_fifosize_arm,
};
@ -109,6 +111,7 @@ static struct vendor_data vendor_st = {
.oversampling = true,
.dma_threshold = true,
.cts_event_workaround = true,
.always_enabled = false,
.get_fifosize = get_fifosize_st,
};
@ -1958,7 +1961,7 @@ static void
pl011_console_write(struct console *co, const char *s, unsigned int count)
{
struct uart_amba_port *uap = amba_ports[co->index];
unsigned int status, old_cr, new_cr;
unsigned int status, old_cr = 0, new_cr;
unsigned long flags;
int locked = 1;
@ -1975,10 +1978,12 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
/*
* First save the CR then disable the interrupts
*/
old_cr = readw(uap->port.membase + UART011_CR);
new_cr = old_cr & ~UART011_CR_CTSEN;
new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
writew(new_cr, uap->port.membase + UART011_CR);
if (!uap->vendor->always_enabled) {
old_cr = readw(uap->port.membase + UART011_CR);
new_cr = old_cr & ~UART011_CR_CTSEN;
new_cr |= UART01x_CR_UARTEN | UART011_CR_TXE;
writew(new_cr, uap->port.membase + UART011_CR);
}
uart_console_write(&uap->port, s, count, pl011_console_putchar);
@ -1989,7 +1994,8 @@ pl011_console_write(struct console *co, const char *s, unsigned int count)
do {
status = readw(uap->port.membase + UART01x_FR);
} while (status & UART01x_FR_BUSY);
writew(old_cr, uap->port.membase + UART011_CR);
if (!uap->vendor->always_enabled)
writew(old_cr, uap->port.membase + UART011_CR);
if (locked)
spin_unlock(&uap->port.lock);