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Date: Thu, 22 Jan 2015 12:24:28 -0500
From: Peter Hurley <peter@...leysoftware.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jslaby@...e.cz>, linux-serial@...r.kernel.org,
linux-kernel@...r.kernel.org,
Peter Hurley <peter@...leysoftware.com>
Subject: [PATCH 4/7] serial: 8250: Refactor divisor programming
Refactor divisor register programming into a new function,
serial8250_set_divisor; this allows serial console to reinitialize
early after resume from suspend.
Signed-off-by: Peter Hurley <peter@...leysoftware.com>
---
drivers/tty/serial/8250/8250_core.c | 87 ++++++++++++++++++++-----------------
1 file changed, 48 insertions(+), 39 deletions(-)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 77afa5f..b8aa6ef 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -2455,6 +2455,50 @@ static unsigned char serial8250_compute_lcr(struct uart_8250_port *up,
return cval;
}
+void serial8250_set_divisor(struct uart_port *port, unsigned int baud,
+ unsigned int quot)
+{
+ struct uart_8250_port *up = up_to_u8250p(port);
+
+ /* Workaround to enable 115200 baud on OMAP1510 internal ports */
+ if (is_omap1510_8250(up)) {
+ if (baud == 115200) {
+ quot = 1;
+ serial_port_out(port, UART_OMAP_OSC_12M_SEL, 1);
+ } else
+ serial_port_out(port, UART_OMAP_OSC_12M_SEL, 0);
+ }
+
+ /*
+ * For NatSemi, switch to bank 2 not bank 1, to avoid resetting EXCR2,
+ * otherwise just set DLAB
+ */
+ if (up->capabilities & UART_NATSEMI)
+ serial_port_out(port, UART_LCR, 0xe0);
+ else
+ serial_port_out(port, UART_LCR, up->lcr | UART_LCR_DLAB);
+
+ serial_dl_write(up, quot);
+
+ /*
+ * XR17V35x UARTs have an extra fractional divisor register (DLD)
+ *
+ * We need to recalculate all of the registers, because DLM and DLL
+ * are already rounded to a whole integer.
+ *
+ * When recalculating we use a 32x clock instead of a 16x clock to
+ * allow 1-bit for rounding in the fractional part.
+ */
+ if (up->port.type == PORT_XR17V35X) {
+ unsigned int baud_x32 = (port->uartclk * 2) / baud;
+ u16 quot = baud_x32 / 32;
+ u8 quot_frac = DIV_ROUND_CLOSEST(baud_x32 % 32, 2);
+
+ serial_dl_write(up, quot);
+ serial_port_out(port, 0x2, quot_frac & 0xf);
+ }
+}
+
void
serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
@@ -2503,6 +2547,8 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
serial8250_rpm_get(up);
spin_lock_irqsave(&port->lock, flags);
+ up->lcr = cval; /* Save computed LCR */
+
/*
* Update the per-port timeout.
*/
@@ -2567,43 +2613,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
serial_port_out(port, UART_EFR, efr);
}
- /* Workaround to enable 115200 baud on OMAP1510 internal ports */
- if (is_omap1510_8250(up)) {
- if (baud == 115200) {
- quot = 1;
- serial_port_out(port, UART_OMAP_OSC_12M_SEL, 1);
- } else
- serial_port_out(port, UART_OMAP_OSC_12M_SEL, 0);
- }
-
- /*
- * For NatSemi, switch to bank 2 not bank 1, to avoid resetting EXCR2,
- * otherwise just set DLAB
- */
- if (up->capabilities & UART_NATSEMI)
- serial_port_out(port, UART_LCR, 0xe0);
- else
- serial_port_out(port, UART_LCR, cval | UART_LCR_DLAB);
-
- serial_dl_write(up, quot);
-
- /*
- * XR17V35x UARTs have an extra fractional divisor register (DLD)
- *
- * We need to recalculate all of the registers, because DLM and DLL
- * are already rounded to a whole integer.
- *
- * When recalculating we use a 32x clock instead of a 16x clock to
- * allow 1-bit for rounding in the fractional part.
- */
- if (up->port.type == PORT_XR17V35X) {
- unsigned int baud_x32 = (port->uartclk * 2) / baud;
- u16 quot = baud_x32 / 32;
- u8 quot_frac = DIV_ROUND_CLOSEST(baud_x32 % 32, 2);
-
- serial_dl_write(up, quot);
- serial_port_out(port, 0x2, quot_frac & 0xf);
- }
+ serial8250_set_divisor(port, baud, quot);
/*
* LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR
@@ -2612,8 +2622,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
if (port->type == PORT_16750)
serial_port_out(port, UART_FCR, up->fcr);
- serial_port_out(port, UART_LCR, cval); /* reset DLAB */
- up->lcr = cval; /* Save LCR */
+ serial_port_out(port, UART_LCR, up->lcr); /* reset DLAB */
if (port->type != PORT_16750) {
/* emulated UARTs (Lucent Venus 167x) need two steps */
if (up->fcr & UART_FCR_ENABLE_FIFO)
--
2.2.2
--
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