| Message ID | 1532939768-7018-2-git-send-email-phil.edworthy@renesas.com (mailing list archive) |
|---|---|
| State | Changes Requested, archived |
| Headers | show |
| Series | Add functions to get optional clocks | expand |
Hi Phil, On Mon, Jul 30, 2018 at 10:36 AM Phil Edworthy <phil.edworthy@renesas.com> wrote: > Quite a few drivers get an optional clock, e.g. a clock required > to access peripheral's registers that is always enabled on some > devices. > > This function behaves the same as of_clk_get_by_name() except that > it will return NULL instead of -ENOENT. This makes error checking > for users easier and allows clk_prepare_enable, etc to be called > on the returned reference without additional checks. > > Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com> Thanks for your patch! > --- a/drivers/clk/clkdev.c > +++ b/drivers/clk/clkdev.c > @@ -54,7 +54,8 @@ EXPORT_SYMBOL(of_clk_get); > > static struct clk *__of_clk_get_by_name(struct device_node *np, > const char *dev_id, > - const char *name) > + const char *name, > + bool optional) > { > struct clk *clk = ERR_PTR(-ENOENT); > > @@ -73,6 +74,8 @@ static struct clk *__of_clk_get_by_name(struct device_node *np, > if (!IS_ERR(clk)) { > break; > } else if (name && index >= 0) { > + if (optional && PTR_ERR(clk) == -ENOENT) > + clk = NULL; This only handles the "name && index >= 0" case. If that condition is never true, the loop will end, eventually, and the last value of clk will be returned. Hence there should be a similar check at the end of the function. > if (PTR_ERR(clk) != -EPROBE_DEFER) > pr_err("ERROR: could not get clock %pOF:%s(%i)\n", > np, name ? name : "", index); Hence if not found, this will always print an error, even if the clock is optional? > @@ -106,15 +109,38 @@ struct clk *of_clk_get_by_name(struct device_node *np, const char *name) > if (!np) > return ERR_PTR(-ENOENT); > > - return __of_clk_get_by_name(np, np->full_name, name); > + return __of_clk_get_by_name(np, np->full_name, name, false); > } > EXPORT_SYMBOL(of_clk_get_by_name); > > +/** > + * of_clk_get_by_name_optional() - Parse and lookup an optional clock referenced > + * by a device node > + * @np: pointer to clock consumer node > + * @name: name of consumer's clock input, or NULL for the first clock reference > + * > + * This function parses the clocks and clock-names properties, > + * and uses them to look up the struct clk from the registered list of clock > + * providers. > + * It behaves the same as of_clk_get_by_name(), except when no clock is found. > + * In this case, instead of returning -ENOENT, it returns NULL. > + */ > +struct clk *of_clk_get_by_name_optional(struct device_node *np, > + const char *name) > +{ > + if (!np) > + return ERR_PTR(-ENOENT); Shouldn't this return NULL? Or let __of_clk_get_by_name() handle that (cfr. above)? Hmm, of_clk_get_by_name() has a similar check, while the current __of_clk_get_by_name() already handle np == NULL, too. > + > + return __of_clk_get_by_name(np, np->full_name, name, true); > +} > +EXPORT_SYMBOL(of_clk_get_by_name_optional); > + > #else /* defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) */ > > static struct clk *__of_clk_get_by_name(struct device_node *np, > const char *dev_id, > - const char *name) > + const char *name, > + bool optional) > { > return ERR_PTR(-ENOENT); > } > @@ -197,7 +223,7 @@ struct clk *clk_get(struct device *dev, const char *con_id) > struct clk *clk; > > if (dev && dev->of_node) { > - clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id); > + clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id, false); > if (!IS_ERR(clk) || PTR_ERR(clk) == -EPROBE_DEFER) > return clk; > } > diff --git a/include/linux/clk.h b/include/linux/clk.h > index 4f750c4..8cb5455 100644 > --- a/include/linux/clk.h > +++ b/include/linux/clk.h > @@ -777,6 +777,7 @@ static inline void clk_bulk_disable_unprepare(int num_clks, > #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) > struct clk *of_clk_get(struct device_node *np, int index); > struct clk *of_clk_get_by_name(struct device_node *np, const char *name); > +struct clk *of_clk_get_by_name_optional(struct device_node *np, const char *name); > struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec); > #else > static inline struct clk *of_clk_get(struct device_node *np, int index) No dummy version of of_clk_get_by_name_optional() for the !CLK || !COMMON_CLK case? It seems of_clk_get_by_name() and of_clk_get_by_name_optional() can just be simple wrappers around __of_clk_get_by_name(), differing only in the value of the "optional" parameter. Hence I think it makes sense to move them to the header file, and make them static inline. Then only __of_clk_get_by_name() needs a (static inline) dummy for the !OF || !COMMON_CLK case. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-clk" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2018-07-30 at 10:55 +0200, Geert Uytterhoeven wrote: > On Mon, Jul 30, 2018 at 10:36 AM Phil Edworthy > <phil.edworthy@renesas.com> wrote: > > +struct clk *of_clk_get_by_name_optional(struct device_node *np, > > + const char *name) > > +{ > > + if (!np) > > + return ERR_PTR(-ENOENT); > > Shouldn't this return NULL? > Or let __of_clk_get_by_name() handle that (cfr. above)? > > Hmm, of_clk_get_by_name() has a similar check, while the current > __of_clk_get_by_name() already handle np == NULL, too. This check is needed to prevent NULL pointer dereference below. And I agree that absence of device node should be considered as okay case for optional clock (!CONFIG_OF case, for example). > > + > > + return __of_clk_get_by_name(np, np->full_name, name, true); > > +}
Hi Andy, On Mon, Jul 30, 2018 at 12:57 PM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > On Mon, 2018-07-30 at 10:55 +0200, Geert Uytterhoeven wrote: > > On Mon, Jul 30, 2018 at 10:36 AM Phil Edworthy > > <phil.edworthy@renesas.com> wrote: > > > > +struct clk *of_clk_get_by_name_optional(struct device_node *np, > > > + const char *name) > > > +{ > > > + if (!np) > > > + return ERR_PTR(-ENOENT); > > > > Shouldn't this return NULL? > > Or let __of_clk_get_by_name() handle that (cfr. above)? > > > > Hmm, of_clk_get_by_name() has a similar check, while the current > > __of_clk_get_by_name() already handle np == NULL, too. > > This check is needed to prevent NULL pointer dereference below. Thank, I had missed that unexpected detail. > > > + > > > + return __of_clk_get_by_name(np, np->full_name, name, true); > > > +} Gr{oetje,eeting}s, Geert
diff --git a/drivers/clk/clkdev.c b/drivers/clk/clkdev.c index 9ab3db8..c1b7262 100644 --- a/drivers/clk/clkdev.c +++ b/drivers/clk/clkdev.c @@ -54,7 +54,8 @@ EXPORT_SYMBOL(of_clk_get); static struct clk *__of_clk_get_by_name(struct device_node *np, const char *dev_id, - const char *name) + const char *name, + bool optional) { struct clk *clk = ERR_PTR(-ENOENT); @@ -73,6 +74,8 @@ static struct clk *__of_clk_get_by_name(struct device_node *np, if (!IS_ERR(clk)) { break; } else if (name && index >= 0) { + if (optional && PTR_ERR(clk) == -ENOENT) + clk = NULL; if (PTR_ERR(clk) != -EPROBE_DEFER) pr_err("ERROR: could not get clock %pOF:%s(%i)\n", np, name ? name : "", index); @@ -106,15 +109,38 @@ struct clk *of_clk_get_by_name(struct device_node *np, const char *name) if (!np) return ERR_PTR(-ENOENT); - return __of_clk_get_by_name(np, np->full_name, name); + return __of_clk_get_by_name(np, np->full_name, name, false); } EXPORT_SYMBOL(of_clk_get_by_name); +/** + * of_clk_get_by_name_optional() - Parse and lookup an optional clock referenced + * by a device node + * @np: pointer to clock consumer node + * @name: name of consumer's clock input, or NULL for the first clock reference + * + * This function parses the clocks and clock-names properties, + * and uses them to look up the struct clk from the registered list of clock + * providers. + * It behaves the same as of_clk_get_by_name(), except when no clock is found. + * In this case, instead of returning -ENOENT, it returns NULL. + */ +struct clk *of_clk_get_by_name_optional(struct device_node *np, + const char *name) +{ + if (!np) + return ERR_PTR(-ENOENT); + + return __of_clk_get_by_name(np, np->full_name, name, true); +} +EXPORT_SYMBOL(of_clk_get_by_name_optional); + #else /* defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) */ static struct clk *__of_clk_get_by_name(struct device_node *np, const char *dev_id, - const char *name) + const char *name, + bool optional) { return ERR_PTR(-ENOENT); } @@ -197,7 +223,7 @@ struct clk *clk_get(struct device *dev, const char *con_id) struct clk *clk; if (dev && dev->of_node) { - clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id); + clk = __of_clk_get_by_name(dev->of_node, dev_id, con_id, false); if (!IS_ERR(clk) || PTR_ERR(clk) == -EPROBE_DEFER) return clk; } diff --git a/include/linux/clk.h b/include/linux/clk.h index 4f750c4..8cb5455 100644 --- a/include/linux/clk.h +++ b/include/linux/clk.h @@ -777,6 +777,7 @@ static inline void clk_bulk_disable_unprepare(int num_clks, #if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK) struct clk *of_clk_get(struct device_node *np, int index); struct clk *of_clk_get_by_name(struct device_node *np, const char *name); +struct clk *of_clk_get_by_name_optional(struct device_node *np, const char *name); struct clk *of_clk_get_from_provider(struct of_phandle_args *clkspec); #else static inline struct clk *of_clk_get(struct device_node *np, int index)
Quite a few drivers get an optional clock, e.g. a clock required to access peripheral's registers that is always enabled on some devices. This function behaves the same as of_clk_get_by_name() except that it will return NULL instead of -ENOENT. This makes error checking for users easier and allows clk_prepare_enable, etc to be called on the returned reference without additional checks. Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com> --- drivers/clk/clkdev.c | 34 ++++++++++++++++++++++++++++++---- include/linux/clk.h | 1 + 2 files changed, 31 insertions(+), 4 deletions(-)