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Subject[RFC 3/8] of: create of_phandle_args to simplify return of phandle parsing data
Date
of_parse_phandle_with_args() needs to return quite a bit of data.  Rather
than making each datum a separate **out_ argument, this patch creates
struct of_phandle_args to contain all the returned data and reworks the
user of the function. This patch also enables of_parse_phandle_with_args()
to return the device node pointer for the phandle node.

This patch also ends up being fairly major surgery to
of_parse_handle_with_args(). The existing structure didn't work well
when extending to use of_phandle_args, and I discovered bugs during testing.
I also took the opportunity to rename the function to be like the
existing of_parse_phandle().

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
---
drivers/of/base.c | 136 +++++++++++++++++++++++--------------------
drivers/of/gpio.c | 43 ++++++--------
include/asm-generic/gpio.h | 5 +-
include/linux/of.h | 11 +++-
include/linux/of_gpio.h | 10 ++-
5 files changed, 110 insertions(+), 95 deletions(-)
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 9b6588e..7fe8397 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -824,17 +824,16 @@ of_parse_phandle(struct device_node *np, const char *phandle_name, int index)
EXPORT_SYMBOL(of_parse_phandle);

/**
- * of_parse_phandles_with_args - Find a node pointed by phandle in a list
+ * of_parse_phandle_with_args - Find a node pointed by phandle in a list
* @np: pointer to a device tree node containing a list
* @list_name: property name that contains a list
* @cells_name: property name that specifies phandles' arguments count
* @index: index of a phandle to parse out
- * @out_node: optional pointer to device_node struct pointer (will be filled)
- * @out_args: optional pointer to arguments pointer (will be filled)
+ * @out_args: optional pointer to output arguments structure (will be filled)
*
* This function is useful to parse lists of phandles and their arguments.
- * Returns 0 on success and fills out_node and out_args, on error returns
- * appropriate errno value.
+ * Returns 0 on success and fills out_args, on error returns appropriate
+ * errno value.
*
* Example:
*
@@ -851,94 +850,105 @@ EXPORT_SYMBOL(of_parse_phandle);
* }
*
* To get a device_node of the `node2' node you may call this:
- * of_parse_phandles_with_args(node3, "list", "#list-cells", 2, &node2, &args);
+ * of_parse_phandle_with_args(node3, "list", "#list-cells", 2, &args);
*/
-int of_parse_phandles_with_args(struct device_node *np, const char *list_name,
+int of_parse_phandle_with_args(struct device_node *np, const char *list_name,
const char *cells_name, int index,
- struct device_node **out_node,
- const void **out_args)
+ struct of_phandle_args *out_args)
{
int ret = -EINVAL;
- const __be32 *list;
- const __be32 *list_end;
- int size;
- int cur_index = 0;
+ const __be32 *list, *list_end;
+ int size, cur_index = 0;
+ uint32_t count = 0;
struct device_node *node = NULL;
- const void *args = NULL;
+ phandle phandle;

+ /* Retrieve the phandle list property */
list = of_get_property(np, list_name, &size);
- if (!list) {
- ret = -ENOENT;
+ if (!list)
goto err0;
- }
list_end = list + size / sizeof(*list);

+ /*
+ * Loop over all the entries in the list, parsing the #cells property
+ * for each one to determine how long each argument list is
+ */
while (list < list_end) {
- const __be32 *cells;
- phandle phandle;
+ count = 0;

+ /*
+ * If phandle is null, then it is an empty entry with no args,
+ * skip forward to the next entry
+ */
phandle = be32_to_cpup(list++);
- args = list;
-
- /* one cell hole in the list = <>; */
- if (!phandle)
- goto next;
-
- node = of_find_node_by_phandle(phandle);
- if (!node) {
- pr_debug("%s: could not find phandle\n",
- np->full_name);
- goto err0;
- }
+ if (phandle) {
+ /*
+ * Find the provider node and parse the #*-cells
+ * property to determine how long the arguements are
+ */
+ node = of_find_node_by_phandle(phandle);
+ if (!node) {
+ pr_debug("%s: could not find phandle\n",
+ np->full_name);
+ ret = -EINVAL;
+ goto err0;
+ }
+ if (of_property_read_u32(node, cells_name, &count)) {
+ pr_debug("%s: could not get %s for %s\n",
+ np->full_name, cells_name,
+ node->full_name);
+ ret = -EINVAL;
+ goto err1;
+ }

- cells = of_get_property(node, cells_name, &size);
- if (!cells || size != sizeof(*cells)) {
- pr_debug("%s: could not get %s for %s\n",
- np->full_name, cells_name, node->full_name);
- goto err1;
+ /*
+ * Make sure that the arguments actually fit in the
+ * remaining property data length
+ */
+ if (list + count > list_end) {
+ pr_debug("%s: insufficient arguments length\n",
+ np->full_name);
+ goto err1;
+ }
}

- list += be32_to_cpup(cells);
- if (list > list_end) {
- pr_debug("%s: insufficient arguments length\n",
- np->full_name);
- goto err1;
- }
-next:
- if (cur_index == index)
+ /*
+ * All of the error cases in the loop bail out to the err
+ * labels, so at this point, the parsing was successful, but
+ * it might be an empty entry
+ */
+ if (cur_index == index) {
+ ret = phandle ? 0 : -ENOENT;
break;
+ }

of_node_put(node);
node = NULL;
- args = NULL;
+ list += count;
cur_index++;
}

- if (!node) {
- /*
- * args w/o node indicates that the loop above has stopped at
- * the 'hole' cell. Report this differently.
- */
- if (args)
- ret = -EEXIST;
- else
- ret = -ENOENT;
+ if (!node)
goto err0;
- }
-
- if (out_node)
- *out_node = node;
- if (out_args)
- *out_args = args;

+ if (out_args) {
+ int i;
+ if (WARN_ON(count > MAX_PHANDLE_ARGS))
+ count = MAX_PHANDLE_ARGS;
+ out_args->np = node;
+ out_args->args_count = count;
+ for (i = 0; i < count; i++)
+ out_args->args[i] = be32_to_cpup(list++);
+ }
return 0;
-err1:
+
+ err1:
of_node_put(node);
-err0:
+ err0:
pr_debug("%s failed with status %d\n", __func__, ret);
return ret;
}
-EXPORT_SYMBOL(of_parse_phandles_with_args);
+EXPORT_SYMBOL(of_parse_phandle_with_args);

/**
* prom_add_property - Add a property to a node
diff --git a/drivers/of/gpio.c b/drivers/of/gpio.c
index ef0105f..244a2b0 100644
--- a/drivers/of/gpio.c
+++ b/drivers/of/gpio.c
@@ -35,32 +35,27 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname,
int index, enum of_gpio_flags *flags)
{
int ret;
- struct device_node *gpio_np;
struct gpio_chip *gc;
- int size;
- const void *gpio_spec;
- const __be32 *gpio_cells;
+ struct of_phandle_args gpiospec;

- ret = of_parse_phandles_with_args(np, propname, "#gpio-cells", index,
- &gpio_np, &gpio_spec);
+ ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
+ &gpiospec);
if (ret) {
pr_debug("%s: can't parse gpios property\n", __func__);
goto err0;
}

- gc = of_node_to_gpiochip(gpio_np);
+ gc = of_node_to_gpiochip(gpiospec.np);
if (!gc) {
pr_debug("%s: gpio controller %s isn't registered\n",
- np->full_name, gpio_np->full_name);
+ np->full_name, gpiospec.np->full_name);
ret = -ENODEV;
goto err1;
}

- gpio_cells = of_get_property(gpio_np, "#gpio-cells", &size);
- if (!gpio_cells || size != sizeof(*gpio_cells) ||
- be32_to_cpup(gpio_cells) != gc->of_gpio_n_cells) {
+ if (gpiospec.args_count != gc->of_gpio_n_cells) {
pr_debug("%s: wrong #gpio-cells for %s\n",
- np->full_name, gpio_np->full_name);
+ np->full_name, gpiospec.np->full_name);
ret = -EINVAL;
goto err1;
}
@@ -69,13 +64,13 @@ int of_get_named_gpio_flags(struct device_node *np, const char *propname,
if (flags)
*flags = 0;

- ret = gc->of_xlate(gc, np, gpio_spec, flags);
+ ret = gc->of_xlate(gc, &gpiospec, flags);
if (ret < 0)
goto err1;

ret += gc->base;
err1:
- of_node_put(gpio_np);
+ of_node_put(gpiospec.np);
err0:
pr_debug("%s exited with status %d\n", __func__, ret);
return ret;
@@ -105,8 +100,8 @@ unsigned int of_gpio_count(struct device_node *np)
do {
int ret;

- ret = of_parse_phandles_with_args(np, "gpios", "#gpio-cells",
- cnt, NULL, NULL);
+ ret = of_parse_phandle_with_args(np, "gpios", "#gpio-cells",
+ cnt, NULL);
/* A hole in the gpios = <> counts anyway. */
if (ret < 0 && ret != -EEXIST)
break;
@@ -127,12 +122,9 @@ EXPORT_SYMBOL(of_gpio_count);
* gpio chips. This function performs only one sanity check: whether gpio
* is less than ngpios (that is specified in the gpio_chip).
*/
-int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
- const void *gpio_spec, u32 *flags)
+int of_gpio_simple_xlate(struct gpio_chip *gc,
+ const struct of_phandle_args *gpiospec, u32 *flags)
{
- const __be32 *gpio = gpio_spec;
- const u32 n = be32_to_cpup(gpio);
-
/*
* We're discouraging gpio_cells < 2, since that way you'll have to
* write your own xlate function (that will have to retrive the GPIO
@@ -144,13 +136,16 @@ int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
return -EINVAL;
}

- if (n > gc->ngpio)
+ if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
+ return -EINVAL;
+
+ if (gpiospec->args[0] > gc->ngpio)
return -EINVAL;

if (flags)
- *flags = be32_to_cpu(gpio[1]);
+ *flags = gpiospec->args[1];

- return n;
+ return gpiospec->args[0];
}
EXPORT_SYMBOL(of_gpio_simple_xlate);

diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index 8c86210..1a2d518 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -4,6 +4,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/errno.h>
+#include <linux/of.h>

#ifdef CONFIG_GPIOLIB

@@ -128,8 +129,8 @@ struct gpio_chip {
*/
struct device_node *of_node;
int of_gpio_n_cells;
- int (*of_xlate)(struct gpio_chip *gc, struct device_node *np,
- const void *gpio_spec, u32 *flags);
+ int (*of_xlate)(struct gpio_chip *gc,
+ const struct of_phandle_args *gpiospec, u32 *flags);
#endif
};

diff --git a/include/linux/of.h b/include/linux/of.h
index 4948552..566deab 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -222,6 +222,13 @@ extern const void *of_get_property(const struct device_node *node,
#define for_each_property(pp, properties) \
for (pp = properties; pp != NULL; pp = pp->next)

+#define MAX_PHANDLE_ARGS 8
+struct of_phandle_args {
+ struct device_node *np;
+ int args_count;
+ uint32_t args[MAX_PHANDLE_ARGS];
+};
+
extern int of_n_addr_cells(struct device_node *np);
extern int of_n_size_cells(struct device_node *np);
extern const struct of_device_id *of_match_node(
@@ -230,9 +237,9 @@ extern int of_modalias_node(struct device_node *node, char *modalias, int len);
extern struct device_node *of_parse_phandle(struct device_node *np,
const char *phandle_name,
int index);
-extern int of_parse_phandles_with_args(struct device_node *np,
+extern int of_parse_phandle_with_args(struct device_node *np,
const char *list_name, const char *cells_name, int index,
- struct device_node **out_node, const void **out_args);
+ struct of_phandle_args *out_args);

extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));
extern int of_alias_get_id(struct device_node *np, const char *stem);
diff --git a/include/linux/of_gpio.h b/include/linux/of_gpio.h
index 52280a2..b254052 100644
--- a/include/linux/of_gpio.h
+++ b/include/linux/of_gpio.h
@@ -18,6 +18,7 @@
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/gpio.h>
+#include <linux/of.h>

struct device_node;

@@ -57,8 +58,9 @@ extern int of_mm_gpiochip_add(struct device_node *np,
extern void of_gpiochip_add(struct gpio_chip *gc);
extern void of_gpiochip_remove(struct gpio_chip *gc);
extern struct gpio_chip *of_node_to_gpiochip(struct device_node *np);
-extern int of_gpio_simple_xlate(struct gpio_chip *gc, struct device_node *np,
- const void *gpio_spec, u32 *flags);
+extern int of_gpio_simple_xlate(struct gpio_chip *gc,
+ const struct of_phandle_args *gpiospec,
+ u32 *flags);

#else /* CONFIG_OF_GPIO */

@@ -75,8 +77,8 @@ static inline unsigned int of_gpio_count(struct device_node *np)
}

static inline int of_gpio_simple_xlate(struct gpio_chip *gc,
- struct device_node *np,
- const void *gpio_spec, u32 *flags)
+ const struct of_phandle_args *gpiospec,
+ u32 *flags)
{
return -ENOSYS;
}
--
1.7.5.4


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