If user supplied serial base address via kernel command line and
at the same time the word 'mmio' is present, use MMIO accessors.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
arch/x86/boot/early_serial_console.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)
diff --git a/arch/x86/boot/early_serial_console.c b/arch/x86/boot/early_serial_console.c
index 6841f14346c2..fa8eb0b4542e 100644
--- a/arch/x86/boot/early_serial_console.c
+++ b/arch/x86/boot/early_serial_console.c
@@ -33,6 +33,20 @@ static void io_serial_out(unsigned long addr, int offset, int value)
outb(value, addr + offset);
}
+static void mem8_serial_out(unsigned long addr, int offset, int value)
+{
+ u8 __iomem *vaddr = (u8 __iomem *)addr;
+ /* shift implied by pointer type */
+ writeb(value, vaddr + offset);
+}
+
+static unsigned int mem8_serial_in(unsigned long addr, int offset)
+{
+ u8 __iomem *vaddr = (u8 __iomem *)addr;
+ /* shift implied by pointer type */
+ return readb(vaddr + offset);
+}
+
static void early_serial_configure(unsigned long port, int baud)
{
unsigned char c;
@@ -59,6 +73,13 @@ static void early_serial_use_io_accessors(void)
serial_out = io_serial_out;
}
+static void early_serial_use_mmio_accessors(void)
+{
+ /* It is memory mapped - assume 8-bit alignment */
+ serial_in = mem8_serial_in;
+ serial_out = mem8_serial_out;
+}
+
static void early_serial_init(unsigned long port, int baud)
{
early_serial_configure(port, baud);
@@ -101,12 +122,16 @@ static void parse_earlyprintk(void)
/*
* make sure we have
* "serial,0x3f8,115200"
+ * "serial,mmio,0xff010180,115200"
* "serial,ttyS0,115200"
* "ttyS0,115200"
*/
if (pos == 7 && !strncmp(arg + pos, "0x", 2)) {
port = parse_serial_port(arg, pos + 0, &pos);
early_serial_use_io_accessors();
+ } else if (pos == 7 && !strncmp(arg + pos, "mmio,0x", 7)) {
+ port = parse_serial_port(arg, pos + 5, &pos);
+ early_serial_use_mmio_accessors();
} else if (!strncmp(arg + pos, "ttyS", 4)) {
static const int bases[] = { 0x3f8, 0x2f8 };
int idx = 0;
--
2.47.2