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Date: Tue, 20 Jan 2015 12:07:57 +0000
From: Alan <gnomes@...rguk.ukuu.org.uk>
To: greg@...ah.com, linux-kernel@...r.kernel.org,
linux-serial@...r.kernel.org
Subject: [PATCH RESEND] Specify PCI based UART for earlyprintk
From: Stuart R. Anderson <stuart.r.anderson@...el.com>
Add support for specifying PCI based UARTs for earlyprintk
using a syntax like "earlyprintk=pciserial,00:18.1,115200",
where 00:18.1 is the BDF of a UART device.
[Slightly tidied from Stuart's original patch]
Signed-off-by: Alan Cox <alan@...ux.intel.com>
---
arch/x86/kernel/early_printk.c | 182 ++++++++++++++++++++++++++++++++++++----
1 file changed, 166 insertions(+), 16 deletions(-)
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 01d1c18..49e071e 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -19,6 +19,7 @@
#include <linux/usb/ehci_def.h>
#include <linux/efi.h>
#include <asm/efi.h>
+#include <asm/pci_x86.h>
/* Simple VGA output */
#define VGABASE (__ISA_IO_base + 0xb8000)
@@ -76,7 +77,7 @@ static struct console early_vga_console = {
/* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
-static int early_serial_base = 0x3f8; /* ttyS0 */
+static unsigned long early_serial_base = 0x3f8; /* ttyS0 */
#define XMTRDY 0x20
@@ -94,13 +95,40 @@ static int early_serial_base = 0x3f8; /* ttyS0 */
#define DLL 0 /* Divisor Latch Low */
#define DLH 1 /* Divisor latch High */
+static void mem32_serial_out(unsigned long addr, int offset, int value)
+{
+ uint32_t *vaddr = (uint32_t *)addr;
+ /* shift implied by pointer type */
+ writel(value, vaddr + offset);
+}
+
+static unsigned int mem32_serial_in(unsigned long addr, int offset)
+{
+ uint32_t *vaddr = (uint32_t *)addr;
+ /* shift implied by pointer type */
+ return readl(vaddr + offset);
+}
+
+static unsigned int io_serial_in(unsigned long addr, int offset)
+{
+ return inb(addr + offset);
+}
+
+static void io_serial_out(unsigned long addr, int offset, int value)
+{
+ outb(value, addr + offset);
+}
+
+static unsigned int (*serial_in)(unsigned long addr, int offset) = io_serial_in;
+static void (*serial_out)(unsigned long addr, int offset, int value) = io_serial_out;
+
static int early_serial_putc(unsigned char ch)
{
unsigned timeout = 0xffff;
- while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
+ while ((serial_in(early_serial_base, LSR) & XMTRDY) == 0 && --timeout)
cpu_relax();
- outb(ch, early_serial_base + TXR);
+ serial_out(early_serial_base, TXR, ch);
return timeout ? 0 : -1;
}
@@ -114,13 +142,28 @@ static void early_serial_write(struct console *con, const char *s, unsigned n)
}
}
+static __init void early_serial_hw_init(unsigned divisor)
+{
+ unsigned char c;
+
+ serial_out(early_serial_base, LCR, 0x3); /* 8n1 */
+ serial_out(early_serial_base, IER, 0); /* no interrupt */
+ serial_out(early_serial_base, FCR, 0); /* no fifo */
+ serial_out(early_serial_base, MCR, 0x3); /* DTR + RTS */
+
+ c = serial_in(early_serial_base, LCR);
+ serial_out(early_serial_base, LCR, c | DLAB);
+ serial_out(early_serial_base, DLL, divisor & 0xff);
+ serial_out(early_serial_base, DLH, (divisor >> 8) & 0xff);
+ serial_out(early_serial_base, LCR, c & ~DLAB);
+}
+
#define DEFAULT_BAUD 9600
static __init void early_serial_init(char *s)
{
- unsigned char c;
unsigned divisor;
- unsigned baud = DEFAULT_BAUD;
+ unsigned long baud = DEFAULT_BAUD;
char *e;
if (*s == ',')
@@ -145,24 +188,124 @@ static __init void early_serial_init(char *s)
s++;
}
- outb(0x3, early_serial_base + LCR); /* 8n1 */
- outb(0, early_serial_base + IER); /* no interrupt */
- outb(0, early_serial_base + FCR); /* no fifo */
- outb(0x3, early_serial_base + MCR); /* DTR + RTS */
+ if (*s) {
+ if (kstrtoul(s, 0, &baud) < 0 || baud == 0)
+ baud = DEFAULT_BAUD;
+ }
+
+ /* Convert from baud to divisor value */
+ divisor = 115200 / baud;
+
+ /* These will always be IO based ports */
+ serial_in = io_serial_in;
+ serial_out = io_serial_out;
+
+ /* Set up the HW */
+ early_serial_hw_init(divisor);
+}
+
+#ifdef CONFIG_PCI
+/*
+ * early_pci_serial_init()
+ *
+ * This function is invoked when the early_printk param starts with "pciserial"
+ * The rest of the param should be ",B:D.F,baud" where B, D & F describe the
+ * location of a PCI device that must be a UART device.
+ */
+static __init void early_pci_serial_init(char *s)
+{
+ unsigned divisor;
+ unsigned long baud = DEFAULT_BAUD;
+ u8 bus, slot, func;
+ uint32_t classcode, bar0;
+ uint16_t cmdreg;
+ char *e;
+
+
+ /*
+ * First, part the param to get the BDF values
+ */
+ if (*s == ',')
+ ++s;
+
+ if (*s == 0)
+ return;
+
+ bus = (u8)simple_strtoul(s, &e, 16);
+ s = e;
+ if (*s != ':')
+ return;
+ ++s;
+ slot = (u8)simple_strtoul(s, &e, 16);
+ s = e;
+ if (*s != '.')
+ return;
+ ++s;
+ func = (u8)simple_strtoul(s, &e, 16);
+ s = e;
+ /* A baud might be following */
+ if (*s == ',')
+ s++;
+
+ /*
+ * Second, find the device from the BDF
+ */
+ cmdreg = read_pci_config(bus, slot, func, PCI_COMMAND);
+ classcode = read_pci_config(bus, slot, func, PCI_CLASS_REVISION);
+ bar0 = read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_0);
+
+ /*
+ * Verify it is a UART type device
+ */
+ if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) &&
+ (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) ||
+ (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */
+ return;
+
+ /*
+ * Determine if it is IO or memory mapped
+ */
+ if (bar0 & 0x01) {
+ /* it is IO mapped */
+ serial_in = io_serial_in;
+ serial_out = io_serial_out;
+ early_serial_base = bar0&0xfffffffc;
+ write_pci_config(bus, slot, func, PCI_COMMAND,
+ cmdreg|PCI_COMMAND_IO);
+ } else {
+ /* It is memory mapped - assume 32-bit alignment */
+ serial_in = mem32_serial_in;
+ serial_out = mem32_serial_out;
+ /* WARNING! assuming the address is always in the first 4G */
+ early_serial_base =
+ (unsigned long)early_ioremap(bar0 & 0xfffffff0, 0x10);
+ write_pci_config(bus, slot, func, PCI_COMMAND,
+ cmdreg|PCI_COMMAND_MEMORY);
+ }
+
+ /*
+ * Lastly, initalize the hardware
+ */
if (*s) {
- baud = simple_strtoul(s, &e, 0);
- if (baud == 0 || s == e)
+ if (strcmp(s, "nocfg") == 0)
+ /* Sometimes, we want to leave the UART alone
+ * and assume the BIOS has set it up correctly.
+ * "nocfg" tells us this is the case, and we
+ * should do no more setup.
+ */
+ return;
+ if (kstrtoul(s, 0, &baud) < 0 || baud == 0)
baud = DEFAULT_BAUD;
}
+ /* Convert from baud to divisor value */
divisor = 115200 / baud;
- c = inb(early_serial_base + LCR);
- outb(c | DLAB, early_serial_base + LCR);
- outb(divisor & 0xff, early_serial_base + DLL);
- outb((divisor >> 8) & 0xff, early_serial_base + DLH);
- outb(c & ~DLAB, early_serial_base + LCR);
+
+ /* Set up the HW */
+ early_serial_hw_init(divisor);
}
+#endif
static struct console early_serial_console = {
.name = "earlyser",
@@ -210,6 +353,13 @@ static int __init setup_early_printk(char *buf)
early_serial_init(buf + 4);
early_console_register(&early_serial_console, keep);
}
+#ifdef CONFIG_PCI
+ if (!strncmp(buf, "pciserial", 9)) {
+ early_pci_serial_init(buf + 9);
+ early_console_register(&early_serial_console, keep);
+ buf += 9; /* Keep from match the above "serial" */
+ }
+#endif
if (!strncmp(buf, "vga", 3) &&
boot_params.screen_info.orig_video_isVGA == 1) {
max_xpos = boot_params.screen_info.orig_video_cols;
--
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