diff options
| -rw-r--r-- | arch/sandbox/dts/test.dts | 1 | ||||
| -rw-r--r-- | doc/README.serial_dt_baud | 41 | ||||
| -rw-r--r-- | drivers/core/ofnode.c | 18 | ||||
| -rw-r--r-- | drivers/serial/Kconfig | 9 | ||||
| -rw-r--r-- | drivers/serial/serial-uclass.c | 49 | ||||
| -rw-r--r-- | include/dm/ofnode.h | 14 | ||||
| -rw-r--r-- | include/env_default.h | 6 | ||||
| -rw-r--r-- | include/serial.h | 7 | ||||
| -rw-r--r-- | test/dm/serial.c | 1 |
9 files changed, 143 insertions, 3 deletions
diff --git a/arch/sandbox/dts/test.dts b/arch/sandbox/dts/test.dts index 2887f6c0e71..c7197795efb 100644 --- a/arch/sandbox/dts/test.dts +++ b/arch/sandbox/dts/test.dts @@ -1572,6 +1572,7 @@ other-node = "/some-bus/c-test@5"; int-values = <0x1937 72993>; u-boot,acpi-ssdt-order = <&acpi_test2 &acpi_test1>; + stdout-path = "serial0:115200n8"; chosen-test { compatible = "denx,u-boot-fdt-test"; reg = <9 1>; diff --git a/doc/README.serial_dt_baud b/doc/README.serial_dt_baud new file mode 100644 index 00000000000..f8768d0e1bc --- /dev/null +++ b/doc/README.serial_dt_baud @@ -0,0 +1,41 @@ +Fetch serial baudrate from DT +----------------------------- + +To support fetching of baudrate from DT, the following is done:- + +The baudrate configured in Kconfig symbol CONFIG_BAUDRATE is taken by default by serial. +If change of baudrate is required then the Kconfig symbol CONFIG_BAUDRATE needs to +changed and U-Boot recompilation is required or the U-Boot environment needs to be updated. + +To avoid this, add support to fetch the baudrate directly from the device tree file and +update the environment. + +The default environment stores the default baudrate value. When default baudrate and dtb +baudrate are not same glitches are seen on the serial. +So, the environment also needs to be updated with the dtb baudrate to avoid the glitches on +the serial which is enabled by OF_SERIAL_BAUD. + +The Kconfig SPL_ENV_SUPPORT needs to be enabled to allow patching in SPL. + +The Kconfig DEFAULT_ENV_IS_RW which is enabled by OF_SERIAL_BAUD with making the environment +writable. + +The ofnode_read_baud() function parses and fetches the baudrate value from the DT. This value +is validated and updated to baudrate during serial init. Padding is added at the end of the +default environment and the dt baudrate is updated with the latest value. + +Example:- + +The serial port options are of the form "bbbbpnf", where "bbbb" is the baud rate, "p" is parity ("n", "o", or "e"), +"n" is number of bits, and "f" is flow control ("r" for RTS or omit it). Default is "115200n8". + +chosen { + bootargs = "earlycon console=ttyPS0,115200 clk_ignore_unused root=/dev/ram0 rw init_fatal_sh=1"; + stdout-path = "serial0:115200n8"; + }; + +From the chosen node, stdout-path property is obtained as string. + + stdout-path = "serial0:115200n8"; + +The string is parsed to get the baudrate 115200. This string is converted to integer and updated to the environment. diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c index 29a42945102..f72ea416cf1 100644 --- a/drivers/core/ofnode.c +++ b/drivers/core/ofnode.c @@ -991,6 +991,24 @@ ofnode ofnode_get_chosen_node(const char *name) return ofnode_path(prop); } +int ofnode_read_baud(void) +{ + const char *str, *p; + u32 baud; + + str = ofnode_read_chosen_string("stdout-path"); + if (!str) + return -EINVAL; + + /* Parse string serial0:115200n8 */ + p = strchr(str, ':'); + if (!p) + return -EINVAL; + + baud = dectoul(p + 1, NULL); + return baud; +} + const void *ofnode_read_aliases_prop(const char *propname, int *sizep) { ofnode node; diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index 8761a645407..6628a887de7 100644 --- a/drivers/serial/Kconfig +++ b/drivers/serial/Kconfig @@ -24,6 +24,15 @@ config BAUDRATE in the SPL stage (most drivers) or for choosing a default baudrate in the absence of an environment setting (serial_mxc.c). +config OF_SERIAL_BAUD + bool "Fetch serial baudrate from device tree" + depends on DM_SERIAL && SPL_ENV_SUPPORT + select DEFAULT_ENV_IS_RW + help + Select this to enable fetching and setting of the baudrate + configured in the DT. Replace the default baudrate with the DT + baudrate and also set it to the environment. + config DEFAULT_ENV_IS_RW bool "Make default environment as writable" help diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c index df6a387284a..e4fa3933bc8 100644 --- a/drivers/serial/serial-uclass.c +++ b/drivers/serial/serial-uclass.c @@ -155,12 +155,61 @@ static void serial_find_console_or_panic(void) } #endif /* CONFIG_SERIAL_PRESENT */ +/** + * check_valid_baudrate() - Check whether baudrate is valid or not + * + * @baud: baud rate to check + * Return: 0 if OK, -ve on error + */ +static int check_valid_baudrate(int baud) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(baudrate_table); ++i) { + if (baud == baudrate_table[i]) + return 0; + } + + return -EINVAL; +} + +int fetch_baud_from_dtb(void) +{ + int baud_value, ret; + + baud_value = ofnode_read_baud(); + ret = check_valid_baudrate(baud_value); + if (ret) + return ret; + + return baud_value; +} + /* Called prior to relocation */ int serial_init(void) { #if CONFIG_IS_ENABLED(SERIAL_PRESENT) serial_find_console_or_panic(); gd->flags |= GD_FLG_SERIAL_READY; + + if (IS_ENABLED(CONFIG_OF_SERIAL_BAUD)) { + int ret = 0; + char *ptr = (char*)&default_environment[0]; + + /* + * Fetch the baudrate from the dtb and update the value in the + * default environment. + */ + ret = fetch_baud_from_dtb(); + if (ret != -EINVAL && ret != -EFAULT) { + gd->baudrate = ret; + + while (*ptr != '\0' && *(ptr + 1) != '\0') + ptr++; + ptr += 2; + sprintf(ptr, "baudrate=%d", gd->baudrate); + } + } serial_setbrg(); #endif diff --git a/include/dm/ofnode.h b/include/dm/ofnode.h index 19e97a90327..5795115c490 100644 --- a/include/dm/ofnode.h +++ b/include/dm/ofnode.h @@ -977,12 +977,22 @@ const char *ofnode_read_chosen_string(const char *propname); ofnode ofnode_get_chosen_node(const char *propname); /** - * ofnode_read_aliases_prop() - get the value of a aliases property + * ofnode_read_baud() - get the baudrate from string value of chosen property * - * This looks for a property within the /aliases node and returns its value + * This looks for stdout-path property within the /chosen node and parses its + * value to return baudrate. * * This only works with the control FDT. * + * Return: baudrate value if found, else -ve error code + */ +int ofnode_read_baud(void); + +/** + * ofnode_read_aliases_prop() - get the value of a aliases property + * + * This looks for a property within the /aliases node and returns its value + * * @propname: Property name to look for * @sizep: Returns size of property, or `FDT_ERR_...` error code if function * returns NULL diff --git a/include/env_default.h b/include/env_default.h index 227cad7c340..2ca4a087d3b 100644 --- a/include/env_default.h +++ b/include/env_default.h @@ -42,7 +42,7 @@ const char default_environment[] = { #if defined(CONFIG_BOOTDELAY) "bootdelay=" __stringify(CONFIG_BOOTDELAY) "\0" #endif -#if defined(CONFIG_BAUDRATE) && (CONFIG_BAUDRATE >= 0) +#if !defined(CONFIG_OF_SERIAL_BAUD) && defined(CONFIG_BAUDRATE) && (CONFIG_BAUDRATE >= 0) "baudrate=" __stringify(CONFIG_BAUDRATE) "\0" #endif #ifdef CONFIG_LOADS_ECHO @@ -119,6 +119,10 @@ const char default_environment[] = { #ifdef CFG_EXTRA_ENV_SETTINGS CFG_EXTRA_ENV_SETTINGS #endif +#ifdef CONFIG_OF_SERIAL_BAUD + /* Padding for baudrate at the end when environment is writable */ + "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0" +#endif "\0" #else /* CONFIG_USE_DEFAULT_ENV_FILE */ #include "generated/defaultenv_autogenerated.h" diff --git a/include/serial.h b/include/serial.h index 205889d28be..d129dc3253c 100644 --- a/include/serial.h +++ b/include/serial.h @@ -339,6 +339,13 @@ int serial_setconfig(struct udevice *dev, uint config); */ int serial_getinfo(struct udevice *dev, struct serial_device_info *info); +/** + * fetch_baud_from_dtb() - Fetch the baudrate value from DT + * + * Return: baudrate if OK, -ve on error + */ +int fetch_baud_from_dtb(void); + void atmel_serial_initialize(void); void mcf_serial_initialize(void); void mpc85xx_serial_initialize(void); diff --git a/test/dm/serial.c b/test/dm/serial.c index 37d17a65f16..34b783e062e 100644 --- a/test/dm/serial.c +++ b/test/dm/serial.c @@ -29,6 +29,7 @@ static int dm_test_serial(struct unit_test_state *uts) &dev_serial)); ut_assertok(serial_tstc()); + ut_asserteq(115200, fetch_baud_from_dtb()); /* * test with default config which is the only one supported by * sandbox_serial driver |