This adds some support into fdtdec for reading GPIO definitions from the fdt. We permit up to FDT_GPIO_MAX GPIOs in the system. Each GPIO is of the form:
gpio-function-name = <phandle gpio_num flags>;
where:
phandle is a pointer to the GPIO node gpio_num is the number of the GPIO (0 to 223) flags is some flags, proposed as follows:
bit meaning 0 0=input, 1=output 1 for output only: inital value of output 2 0=polarity normal, 1=active low (inverted)
An example is:
enable-propounder = <&gpio 43 1>;
which means that GPIO 43 is an output and we can enable the propounder by setting gpio 43 high.
Two main functions are provided:
fdtdec_decode_gpio() reads a GPIO property from an fdt node and decodes it into a structure.
fdtdec_setup_gpio() sets up the GPIO by calling gpio_request and gpio_direction_input/output() for you.
Both functions can cope with the property being missing, which is taken to mean that that GPIO function is not available or is not needed.
Signed-off-by: Simon Glass sjg@chromium.org ---
include/fdtdec.h | 49 ++++++++++++++++++++++++++++++++ lib/fdtdec.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 132 insertions(+), 0 deletions(-)
diff --git a/include/fdtdec.h b/include/fdtdec.h index 974520a..57db42b 100644 --- a/include/fdtdec.h +++ b/include/fdtdec.h @@ -61,6 +61,26 @@ enum fdt_compat_id { COMPAT_COUNT, };
+/* For now we allow 224 GPIOs. We can extend this later if required */ +enum { + FDT_GPIO_NONE = 255, /* an invalid GPIO used to end our list */ + FDT_GPIO_MAX = 224, /* maximum valid GPIO number */ + + FDT_GPIO_OUTPUT = 1 << 0, /* set as output (else input) */ + FDT_GPIO_HIGH = 1 << 1, /* set output as high (else low) */ + FDT_GPIO_ACTIVE_LOW = 1 << 2, /* input is active low (else high) */ +}; + +/* This is the state of a GPIO pin as defined by the fdt */ +struct fdt_gpio_state { + const char *name; /* name of the fdt property defining this */ + u8 gpio; /* GPIO number, or FDT_GPIO_NONE if none */ + u8 flags; /* FDT_GPIO_... flags */ +}; + +/* This tells us whether a fdt_gpio_state record is valid or not */ +#define fdt_gpio_isvalid(x) ((x)->gpio != FDT_GPIO_NONE) + /** * Find the next numbered alias for a peripheral. This is used to enumerate * all the peripherals of a certain type. @@ -181,3 +201,32 @@ int fdtdec_get_int_array(const void *blob, int node, const char *prop_name, * @return 1 if the properly is present; 0 if it isn't present or is 0 */ int fdtdec_get_bool(const void *blob, int node, const char *prop_name); + +/** + * Decode a single GPIOs from an FDT. + * + * If the property is not found, then the GPIO structure will still be + * initialised, with gpio set to FDT_GPIO_NONE. This makes it easy to + * provide optional GPIOs. + * + * @param blob FDT blob to use + * @param node Node to look at + * @param prop_name Node property name + * @param gpio gpio elements to fill from FDT + * @return 0 if ok, -FDT_ERR_NOTFOUND if the property is missing. + */ +int fdtdec_decode_gpio(const void *blob, int node, const char *prop_name, + struct fdt_gpio_state *gpio); + +/** + * Set up a GPIO pin according to the provided gpio information. This sets it + * to either input or output. If an output, then the defined value is + * assigned. + * + * If the gpio is FDT_GPIO_NONE, no action is taken. This makes it easy to + * deal with optional GPIOs. + * + * @param gpio GPIO info to use for set up + * @return 0 if all ok or gpio was FDT_GPIO_NONE; -1 on error + */ +int fdtdec_setup_gpio(struct fdt_gpio_state *gpio); diff --git a/lib/fdtdec.c b/lib/fdtdec.c index 8f972b7..8eed752 100644 --- a/lib/fdtdec.c +++ b/lib/fdtdec.c @@ -24,6 +24,9 @@ #include <libfdt.h> #include <fdtdec.h>
+/* we need the generic GPIO interface here */ +#include <asm-generic/gpio.h> + DECLARE_GLOBAL_DATA_PTR;
/* @@ -231,3 +234,83 @@ int fdtdec_get_bool(const void *blob, int node, const char *prop_name)
return 1; } + +/** + * Decode a list of GPIOs from an FDT. This creates a list of GPIOs with no + * terminating item. + * + * @param blob FDT blob to use + * @param node Node to look at + * @param prop_name Node property name + * @param gpio Array of gpio elements to fill from FDT. This will be + * untouched if either 0 or an error is returned + * @param max_count Maximum number of elements allowed + * @return number of GPIOs read if ok, -FDT_ERR_BADLAYOUT if max_count would + * be exceeded, or -FDT_ERR_NOTFOUND if the property is missing. + */ +static int fdtdec_decode_gpios(const void *blob, int node, + const char *prop_name, struct fdt_gpio_state *gpio, + int max_count) +{ + const struct fdt_property *prop; + const u32 *cell; + const char *name; + int len, i; + + debug("%s: %s\n", __func__, prop_name); + assert(max_count > 0); + prop = fdt_get_property(blob, node, prop_name, &len); + if (!prop) { + debug("FDT: %s: property '%s' missing\n", __func__, prop_name); + return -FDT_ERR_NOTFOUND; + } + + /* We will use the name to tag the GPIO */ + name = fdt_string(blob, prop->nameoff); + cell = (u32 *)prop->data; + len /= sizeof(u32) * 3; /* 3 cells per GPIO record */ + if (len > max_count) { + debug("FDT: %s: too many GPIOs / cells for " + "property '%s'\n", __func__, prop_name); + return -FDT_ERR_BADLAYOUT; + } + + /* Read out the GPIO data from the cells */ + for (i = 0; i < len; i++, cell += 3) { + gpio[i].gpio = fdt32_to_cpu(cell[1]); + gpio[i].flags = fdt32_to_cpu(cell[2]); + gpio[i].name = name; + } + + return len; +} + +int fdtdec_decode_gpio(const void *blob, int node, const char *prop_name, + struct fdt_gpio_state *gpio) +{ + int err; + + debug("%s: %s\n", __func__, prop_name); + gpio->gpio = FDT_GPIO_NONE; + err = fdtdec_decode_gpios(blob, node, prop_name, gpio, 1); + return err == 1 ? 0 : err; +} + +int fdtdec_setup_gpio(struct fdt_gpio_state *gpio) +{ + /* + * Return success if there is no GPIO defined. This is used for + * optional GPIOs) + */ + if (!fdt_gpio_isvalid(gpio)) + return 0; + + if (gpio_request(gpio->gpio, gpio->name)) + return -1; + if (gpio->flags & FDT_GPIO_OUTPUT) { + return gpio_direction_output(gpio->gpio, + gpio->flags & FDT_GPIO_HIGH); + } else { + return gpio_direction_input(gpio->gpio); + } +}