MIPS: SEAD3: Probe UARTs using DT
Probe the UARTs on SEAD3 boards using device tree rather than platform
code, in order to reduce the amount of the latter. This requires that
CONFIG_SERIAL_OF_PLATFORM be enabled, so enable it in sead3_defconfig.
The SEAD3 DT shim code is extended to read bootloader environment
variables to determine the appropriate UART & mode for kernel console
output & set the stdout-path property of the chosen node accordingly.
In contrast to the old platform code, which appears to have only ever
set "console=ttyS0,38400n8r" with the code in console_config never
having an effect, this will honor the "yamontty" environment variable to
select between the 2 UARTs on the board and then check the "modetty0" or
"modetty1" variable as appropriate to determine the UART configuration.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14048/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mti-sead3/sead3-dtshim.c b/arch/mips/mti-sead3/sead3-dtshim.c
index 3283a7e..b462f65 100644
--- a/arch/mips/mti-sead3/sead3-dtshim.c
+++ b/arch/mips/mti-sead3/sead3-dtshim.c
@@ -14,6 +14,7 @@
#include <linux/libfdt.h>
#include <linux/printk.h>
+#include <asm/fw/fw.h>
#include <asm/io.h>
#define SEAD_CONFIG CKSEG1ADDR(0x1b100110)
@@ -23,7 +24,8 @@
static int remove_gic(void *fdt)
{
- int gic_off, cpu_off, err;
+ const unsigned int cpu_uart_int = 4;
+ int gic_off, cpu_off, uart_off, err;
uint32_t cfg, cpu_phandle;
/* leave the GIC node intact if a GIC is present */
@@ -62,6 +64,103 @@
return err;
}
+ uart_off = fdt_node_offset_by_compatible(fdt, -1, "ns16550a");
+ while (uart_off >= 0) {
+ err = fdt_setprop_u32(fdt, uart_off, "interrupts",
+ cpu_uart_int);
+ if (err) {
+ pr_err("unable to set UART interrupts property: %d\n",
+ err);
+ return err;
+ }
+
+ uart_off = fdt_node_offset_by_compatible(fdt, uart_off,
+ "ns16550a");
+ }
+ if (uart_off != -FDT_ERR_NOTFOUND) {
+ pr_err("error searching for UART DT node: %d\n", uart_off);
+ return uart_off;
+ }
+
+ return 0;
+}
+
+static int serial_config(void *fdt)
+{
+ const char *yamontty, *mode_var;
+ char mode_var_name[9], path[18], parity;
+ unsigned int uart, baud, stop_bits;
+ bool hw_flow;
+ int chosen_off, err;
+
+ yamontty = fw_getenv("yamontty");
+ if (!yamontty || !strcmp(yamontty, "tty0")) {
+ uart = 0;
+ } else if (!strcmp(yamontty, "tty1")) {
+ uart = 1;
+ } else {
+ pr_warn("yamontty environment variable '%s' invalid\n",
+ yamontty);
+ uart = 0;
+ }
+
+ baud = stop_bits = 0;
+ parity = 0;
+ hw_flow = false;
+
+ snprintf(mode_var_name, sizeof(mode_var_name), "modetty%u", uart);
+ mode_var = fw_getenv(mode_var_name);
+ if (mode_var) {
+ while (mode_var[0] >= '0' && mode_var[0] <= '9') {
+ baud *= 10;
+ baud += mode_var[0] - '0';
+ mode_var++;
+ }
+ if (mode_var[0] == ',')
+ mode_var++;
+ if (mode_var[0])
+ parity = mode_var[0];
+ if (mode_var[0] == ',')
+ mode_var++;
+ if (mode_var[0])
+ stop_bits = mode_var[0] - '0';
+ if (mode_var[0] == ',')
+ mode_var++;
+ if (!strcmp(mode_var, "hw"))
+ hw_flow = true;
+ }
+
+ if (!baud)
+ baud = 38400;
+
+ if (parity != 'e' && parity != 'n' && parity != 'o')
+ parity = 'n';
+
+ if (stop_bits != 7 && stop_bits != 8)
+ stop_bits = 8;
+
+ WARN_ON(snprintf(path, sizeof(path), "uart%u:%u%c%u%s",
+ uart, baud, parity, stop_bits,
+ hw_flow ? "r" : "") >= sizeof(path));
+
+ /* find or add chosen node */
+ chosen_off = fdt_path_offset(fdt, "/chosen");
+ if (chosen_off == -FDT_ERR_NOTFOUND)
+ chosen_off = fdt_path_offset(fdt, "/chosen@0");
+ if (chosen_off == -FDT_ERR_NOTFOUND)
+ chosen_off = fdt_add_subnode(fdt, 0, "chosen");
+ if (chosen_off < 0) {
+ pr_err("Unable to find or add DT chosen node: %d\n",
+ chosen_off);
+ return chosen_off;
+ }
+
+ err = fdt_setprop_string(fdt, chosen_off, "stdout-path", path);
+ if (err) {
+ pr_err("Unable to set stdout-path property: %d\n", err);
+ return err;
+ }
+
return 0;
}
@@ -84,6 +183,10 @@
if (err)
panic("Unable to patch FDT: %d", err);
+ err = serial_config(fdt_buf);
+ if (err)
+ panic("Unable to patch FDT: %d", err);
+
err = fdt_pack(fdt_buf);
if (err)
panic("Unable to pack FDT: %d\n", err);