Commit 857dde2e authored by David Woodhouse's avatar David Woodhouse Committed by Russell King
Browse files

When we detect that a 16550 was in fact part of a NatSemi SuperIO chip 


with high-speed mode enabled, we switch it to high-speed mode so that
baud_base becomes 921600. However, we also need to multiply the baud
divisor by 8 at the same time, in case it's already in use as a console.

Signed-off-by: David Woodhouse
Acked-by: Tom Rini
Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 9636273d

drivers/serial/8250.c

+12 −5
Original line number Diff line number Diff line
@@ -682,8 +682,6 @@ static void autoconfig_16550a(struct uart_8250_port *up) 
	 * from EXCR1. Switch back to bank 0, change it in MCR. Then

	 * switch back to bank 2, read it from EXCR1 again and check

	 * it's changed. If so, set baud_base in EXCR2 to 921600. -- dwmw2

	 * On PowerPC we don't want to change baud_base, as we have

	 * a number of different divisors.  -- Tom Rini

	 */

	serial_outp(up, UART_LCR, 0);

	status1 = serial_in(up, UART_MCR);
@@ -699,16 +697,25 @@ static void autoconfig_16550a(struct uart_8250_port *up) 
		serial_outp(up, UART_MCR, status1);



		if ((status2 ^ status1) & UART_MCR_LOOP) {

#ifndef CONFIG_PPC

			unsigned short quot;



			serial_outp(up, UART_LCR, 0xE0);



			quot = serial_inp(up, UART_DLM) << 8;

			quot += serial_inp(up, UART_DLL);

			quot <<= 3;



			status1 = serial_in(up, 0x04); /* EXCR1 */

			status1 &= ~0xB0; /* Disable LOCK, mask out PRESL[01] */

			status1 |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */

			serial_outp(up, 0x04, status1);

			

			serial_outp(up, UART_DLL, quot & 0xff);

			serial_outp(up, UART_DLM, quot >> 8);



			serial_outp(up, UART_LCR, 0);

			up->port.uartclk = 921600*16;

#endif



			up->port.uartclk = 921600*16;

			up->port.type = PORT_NS16550A;

			up->capabilities |= UART_NATSEMI;

			return;

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