[PATCH v3 4/4] x86, earlyprintk: add hsu early console for Intel Medfield platform

Feng Tang
2010-09-13T06:49:06Z

Intel Medfield platform has a high speed UART device, which could act
as a early console. To enable early printk of HSU console, simply add
"earlyprintk=hsu" in kernel command line.

Currently we put the code in the early_printk_mrst.c as it is also for
Intel MID platforms like the mrst early console

Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: x86 maintainers <x86@kernel.org>
Signed-off-by: Alan Cox <alan@linux.intel.com>
---
arch/x86/include/asm/mrst.h | 3 +
arch/x86/kernel/early_printk.c | 6 ++
arch/x86/kernel/early_printk_mrst.c | 89 ++++++++++++++++++++++++++++++++++-
3 files changed, 97 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/mrst.h b/arch/x86/include/asm/mrst.h
index d0ea5bc..4a711a6 100644
--- a/arch/x86/include/asm/mrst.h
+++ b/arch/x86/include/asm/mrst.h
@@ -47,4 +47,7 @@ extern enum mrst_timer_options mrst_timer_options;

extern struct console early_mrst_console;
extern void mrst_early_console_init(void);
+
+extern struct console early_hsu_console;
+extern void hsu_early_console_init(void);
#endif /* _ASM_X86_MRST_H */
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 6082463..4572f25 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -245,6 +245,12 @@ static int __init setup_early_printk(char *buf)
mrst_early_console_init();
early_console_register(&early_mrst_console, keep);
}
+
+ if (!strncmp(buf, "hsu", 3)) {
+ hsu_early_console_init();
+ early_console_register(&early_hsu_console, keep);
+ }
+
#endif
buf++;
}
diff --git a/arch/x86/kernel/early_printk_mrst.c b/arch/x86/kernel/early_printk_mrst.c
index 05d27e1..65df603 100644
--- a/arch/x86/kernel/early_printk_mrst.c
+++ b/arch/x86/kernel/early_printk_mrst.c
@@ -1,5 +1,5 @@
/*
- * early_printk_mrst.c - spi-uart early printk for Intel Moorestown platform
+ * early_printk_mrst.c - early consoles for Intel MID platforms
*
* Copyright (c) 2008-2010, Intel Corporation
*
@@ -9,9 +9,19 @@
* of the License.
*/

+/*
+ * This file implements two early consoles named mrst and hsu.
+ * mrst is based on Maxim3110 spi-uart device, it exists in both
+ * Moorestown and Medfield platforms, while hsu is based on a High
+ * Speed UART device which only exists in the Medfield platform
+ */
+
+#include <linux/serial_reg.h>
+#include <linux/serial_mfd.h>
#include <linux/kmsg_dump.h>
#include <linux/console.h>
#include <linux/kernel.h>
+#include <linux/delay.h>
#include <linux/init.h>
#include <linux/io.h>

@@ -230,3 +240,80 @@ struct console early_mrst_console = {
.flags = CON_PRINTBUFFER,
.index = -1,
};
+
+/*
+ * Following is the early console based on Medfield HSU (High
+ * Speed UART) device.
+ */
+#define HSU_PORT2_PADDR 0xffa28180
+
+static void __iomem *phsu;
+
+void hsu_early_console_init(void)
+{
+ u8 lcr;
+
+ phsu = (void *)set_fixmap_offset_nocache(FIX_EARLYCON_MEM_BASE,
+ HSU_PORT2_PADDR);
+
+ /* Disable FIFO */
+ writeb(0x0, phsu + UART_FCR);
+
+ /* Set to default 115200 bps, 8n1 */
+ lcr = readb(phsu + UART_LCR);
+ writeb((0x80 | lcr), phsu + UART_LCR);
+ writeb(0x18, phsu + UART_DLL);
+ writeb(lcr, phsu + UART_LCR);
+ writel(0x3600, phsu + UART_MUL*4);
+
+ writeb(0x8, phsu + UART_MCR);
+ writeb(0x7, phsu + UART_FCR);
+ writeb(0x3, phsu + UART_LCR);
+
+ /* Clear IRQ status */
+ readb(phsu + UART_LSR);
+ readb(phsu + UART_RX);
+ readb(phsu + UART_IIR);
+ readb(phsu + UART_MSR);
+
+ /* Enable FIFO */
+ writeb(0x7, phsu + UART_FCR);
+}
+
+#define BOTH_EMPTY (UART_LSR_TEMT | UART_LSR_THRE)
+
+static void early_hsu_putc(char ch)
+{
+ unsigned int timeout = 10000; /* 10ms */
+ u8 status;
+
+ while (--timeout) {
+ status = readb(phsu + UART_LSR);
+ if (status & BOTH_EMPTY)
+ break;
+ udelay(1);
+ }
+
+ /* Only write the char when there was no timeout */
+ if (timeout)
+ writeb(ch, phsu + UART_TX);
+}
+
+static void early_hsu_write(struct console *con, const char *str, unsigned n)
+{
+ int i;
+
+ for (i = 0; i < n && *str; i++) {
+ if (*str == '\n')
+ early_hsu_putc('\r');
+ early_hsu_putc(*str);
+ str++;
+ }
+}
+
+struct console early_hsu_console = {
+ .name = "earlyhsu",
+ .write = early_hsu_write,
+ .flags = CON_PRINTBUFFER,
+ .index = -1,
+};
--
1.7.0.4