| Message ID | 1392829124-25705-4-git-send-email-s.nawrocki@samsung.com |
|---|---|
| State | Superseded, archived |
| Headers | show |
On Wed, 19 Feb 2014 17:58:44 +0100, Sylwester Nawrocki <s.nawrocki@samsung.com> wrote: > This function adds a notifier callback run before a driver is bound to > its driver. It will configure parent clock and clock frequencies based > on [clk-name]-clk-parent and [clk-name]-clk-rate' DT properties. > > Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com> > Acked-by: Kyungmin Park <kyungmin.park@samsung.com> > --- > .../devicetree/bindings/clock/clock-bindings.txt | 24 +++++ > drivers/clk/clk.c | 92 ++++++++++++++++++++ > 2 files changed, 116 insertions(+) > > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > index 7c52c29..d618498 100644 > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > @@ -115,3 +115,27 @@ clock signal, and a UART. > ("pll" and "pll-switched"). > * The UART has its baud clock connected the external oscillator and its > register clock connected to the PLL clock (the "pll-switched" signal) > + > +==Static initial configuration of clock parent and clock frequency== > + > +Some platforms require static configuration of (parts of) the clock controller > +often determined by the board design. Such a configuration can be specified in > +a clock consumer node through [clk-name]-clk-parent and [clk-name]-clk-rate DT > +properties. The former should contain phandle and clock specifier of the parent > +clock, the latter the required clock's frequency value (one cell). "clk-name" > +should be listed in the clock-names property and a phandle and a clock specifier > +pair corresponding to it should be present in the clocks property. > + > + uart@a000 { > + compatible = "fsl,imx-uart"; > + reg = <0xa000 0x1000>; > + ... > + clocks = <&clkcon 0>, <&clkcon 3>; > + clock-names = "baud", "mux"; > + > + mux-clk-parent = <&pll 1>; > + baud-clk-rate = <460800>; This mixes patterns for references to clocks. Plus it requires composing property names which is a little painful. I'd rather see a list of tuples to match the existing pattern already in use clocks = <&clkcon 0>, <&clkcon 3>; clock-names = "baud", "mux"; clock-parents = <0> <&pll 1>; clock-rates = <0> <460800>; g. > + }; > + > +In this example the pll is set as parent of "mux" clock and frequency of "baud" > +clock is specified as 460800 Hz. > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index 19f6f3f..9238e08 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -19,6 +19,7 @@ > #include <linux/of.h> > #include <linux/device.h> > #include <linux/init.h> > +#include <linux/platform_device.h> > #include <linux/sched.h> > > #include "clk.h" > @@ -2527,6 +2528,97 @@ const char *of_clk_get_parent_name(struct device_node *np, int index) > } > EXPORT_SYMBOL_GPL(of_clk_get_parent_name); > > +static void __of_clk_assigned_config_set(struct clk *clk, struct clk *pclk, > + u32 rate) > +{ > + int rc; > + > + if (rate) { > + rc = clk_set_rate(clk, rate); > + if (rc < 0) > + pr_err("clk: couldn't set rate of clock %s (%d)\n", > + __clk_get_name(clk), rc); > + else > + pr_debug("clk: set rate of clock %s to %u\n", > + __clk_get_name(clk), rate); > + } > + > + if (!IS_ERR(pclk)) { > + rc = clk_set_parent(clk, pclk); > + if (rc < 0) > + pr_err("clk: couldn't set %s as parent of %s (%d)\n", > + __clk_get_name(pclk), __clk_get_name(clk), rc); > + else > + pr_debug("clk: set %s as parent of %s\n", > + __clk_get_name(pclk), __clk_get_name(clk)); > + } > +} > + > +static void of_clk_assigned_config_parse(struct device_node *node) > +{ > + char prop_name[OF_PROP_NAME_MAXLEN]; > + struct property *prop; > + const char *clk_name; > + int rc, index = 0; > + > + of_property_for_each_string(node, "clock-names", prop, clk_name) { > + struct clk *clk, *pclk; > + u32 rate = 0; > + > + snprintf(prop_name, OF_PROP_NAME_MAXLEN, > + "%s-clk-parent", clk_name); > + pclk = of_clk_get_list_entry(node, prop_name, 0); > + > + snprintf(prop_name, OF_PROP_NAME_MAXLEN, > + "%s-clk-rate", clk_name); > + rc = of_property_read_u32(node, prop_name, &rate); > + > + if (!rc || !IS_ERR(pclk)) { > + /* > + * Assuming here of_property_for_each_string() returns > + * consecutive values of a DT property in ascending > + * index order. > + */ > + clk = of_clk_get(node, index); > + > + if (!IS_ERR(clk)) > + __of_clk_assigned_config_set(clk, pclk, rate); > + else > + pr_err("clk: couldn't get clk %s\n", clk_name); > + } > + index++; > + } > +} > + > + > +static int of_clk_setup_notifier_call(struct notifier_block *nb, > + unsigned long event, void *data) > +{ > + struct device *dev = data; > + > + if (!dev->of_node) > + return NOTIFY_DONE; > + > + switch (event) { > + case BUS_NOTIFY_BIND_DRIVER: > + /* Parse and configure DT assigned clock parents and rates */ > + of_clk_assigned_config_parse(dev->of_node); > + break; > + } > + > + return NOTIFY_DONE; > +} > + > +static struct notifier_block of_clk_setup_nb = { > + .notifier_call = of_clk_setup_notifier_call, > +}; > + > +int __init of_clk_setup_notifier_init(void) > +{ > + return bus_register_notifier(&platform_bus_type, &of_clk_setup_nb); > +} > +subsys_initcall(of_clk_setup_notifier_init); > + > /** > * of_clk_init() - Scan and init clock providers from the DT > * @matches: array of compatible values and init functions for providers. > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 20/02/14 15:09, Grant Likely wrote: [...] >> > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt >> > index 7c52c29..d618498 100644 >> > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt >> > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt >> > @@ -115,3 +115,27 @@ clock signal, and a UART. >> > ("pll" and "pll-switched"). >> > * The UART has its baud clock connected the external oscillator and its >> > register clock connected to the PLL clock (the "pll-switched" signal) >> > + >> > +==Static initial configuration of clock parent and clock frequency== >> > + >> > +Some platforms require static configuration of (parts of) the clock controller >> > +often determined by the board design. Such a configuration can be specified in >> > +a clock consumer node through [clk-name]-clk-parent and [clk-name]-clk-rate DT >> > +properties. The former should contain phandle and clock specifier of the parent >> > +clock, the latter the required clock's frequency value (one cell). "clk-name" >> > +should be listed in the clock-names property and a phandle and a clock specifier >> > +pair corresponding to it should be present in the clocks property. >> > + >> > + uart@a000 { >> > + compatible = "fsl,imx-uart"; >> > + reg = <0xa000 0x1000>; >> > + ... >> > + clocks = <&clkcon 0>, <&clkcon 3>; >> > + clock-names = "baud", "mux"; >> > + >> > + mux-clk-parent = <&pll 1>; >> > + baud-clk-rate = <460800>; > > This mixes patterns for references to clocks. Plus it requires composing > property names which is a little painful. I'd rather see a list of > tuples to match the existing pattern already in use > > clocks = <&clkcon 0>, <&clkcon 3>; > clock-names = "baud", "mux"; > clock-parents = <0> <&pll 1>; > clock-rates = <0> <460800>; Thank you for the review. This looks much better to me. My bad, I wasn't aware 0 can be used to denote an empty phandle like this. ePAPR seems not to be specifying exact meaning of the 'phandle' property values, except they be unique. Anyway, it seems to be clearly documented within the __of_parse_phandle_with_args() function. I'll try this modified binding instead, presumably it would be useful to have a variant of __of_parse_phandle_with_args() function which would accept a context data containing result of previous call within an iteration, similarly as of_property_next_string() is written. So we don't iterate from beginning of the list with each __of_parse_phandle_with_args() call. But it's an optimization issue that could be considered separately I guess. -- Thanks, Sylwester -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Quoting Sylwester Nawrocki (2014-02-21 02:38:21) > On 20/02/14 15:09, Grant Likely wrote: > [...] > >> > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > >> > index 7c52c29..d618498 100644 > >> > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt > >> > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > >> > @@ -115,3 +115,27 @@ clock signal, and a UART. > >> > ("pll" and "pll-switched"). > >> > * The UART has its baud clock connected the external oscillator and its > >> > register clock connected to the PLL clock (the "pll-switched" signal) > >> > + > >> > +==Static initial configuration of clock parent and clock frequency== > >> > + > >> > +Some platforms require static configuration of (parts of) the clock controller > >> > +often determined by the board design. Such a configuration can be specified in > >> > +a clock consumer node through [clk-name]-clk-parent and [clk-name]-clk-rate DT > >> > +properties. The former should contain phandle and clock specifier of the parent > >> > +clock, the latter the required clock's frequency value (one cell). "clk-name" > >> > +should be listed in the clock-names property and a phandle and a clock specifier > >> > +pair corresponding to it should be present in the clocks property. > >> > + > >> > + uart@a000 { > >> > + compatible = "fsl,imx-uart"; > >> > + reg = <0xa000 0x1000>; > >> > + ... > >> > + clocks = <&clkcon 0>, <&clkcon 3>; > >> > + clock-names = "baud", "mux"; > >> > + > >> > + mux-clk-parent = <&pll 1>; > >> > + baud-clk-rate = <460800>; > > > > This mixes patterns for references to clocks. Plus it requires composing > > property names which is a little painful. I'd rather see a list of > > tuples to match the existing pattern already in use > > > > clocks = <&clkcon 0>, <&clkcon 3>; > > clock-names = "baud", "mux"; > > clock-parents = <0> <&pll 1>; > > clock-rates = <0> <460800>; > > Thank you for the review. This looks much better to me. My bad, I wasn't > aware 0 can be used to denote an empty phandle like this. ePAPR seems not > to be specifying exact meaning of the 'phandle' property values, except > they be unique. Anyway, it seems to be clearly documented within the > __of_parse_phandle_with_args() function. > > I'll try this modified binding instead, presumably it would be useful to > have a variant of __of_parse_phandle_with_args() function which would > accept a context data containing result of previous call within an iteration, > similarly as of_property_next_string() is written. So we don't iterate > from beginning of the list with each __of_parse_phandle_with_args() call. > But it's an optimization issue that could be considered separately I guess. I was always partial to the regulator style of blahblah-supply but Grant's suggestion is much cleaner with respect to the rest of the clock binding. I guess it will be a bit ugly if a very long array is needed with a sparse attribute. E.g. 20 clocks specified in the 'clocks' property and only a single clock needs to have its parent or rate specified. Is there a reason not to support both methods? Regards, Mike > > -- > Thanks, > Sylwester -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 24/02/14 01:48, Mike Turquette wrote: > Quoting Sylwester Nawrocki (2014-02-21 02:38:21) >> > On 20/02/14 15:09, Grant Likely wrote: >> > [...] >>>>> > >> > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt >>>>> > >> > index 7c52c29..d618498 100644 >>>>> > >> > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt >>>>> > >> > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt >>>>> > >> > @@ -115,3 +115,27 @@ clock signal, and a UART. >>>>> > >> > ("pll" and "pll-switched"). >>>>> > >> > * The UART has its baud clock connected the external oscillator and its >>>>> > >> > register clock connected to the PLL clock (the "pll-switched" signal) >>>>> > >> > + >>>>> > >> > +==Static initial configuration of clock parent and clock frequency== >>>>> > >> > + >>>>> > >> > +Some platforms require static configuration of (parts of) the clock controller >>>>> > >> > +often determined by the board design. Such a configuration can be specified in >>>>> > >> > +a clock consumer node through [clk-name]-clk-parent and [clk-name]-clk-rate DT >>>>> > >> > +properties. The former should contain phandle and clock specifier of the parent >>>>> > >> > +clock, the latter the required clock's frequency value (one cell). "clk-name" >>>>> > >> > +should be listed in the clock-names property and a phandle and a clock specifier >>>>> > >> > +pair corresponding to it should be present in the clocks property. >>>>> > >> > + >>>>> > >> > + uart@a000 { >>>>> > >> > + compatible = "fsl,imx-uart"; >>>>> > >> > + reg = <0xa000 0x1000>; >>>>> > >> > + ... >>>>> > >> > + clocks = <&clkcon 0>, <&clkcon 3>; >>>>> > >> > + clock-names = "baud", "mux"; >>>>> > >> > + >>>>> > >> > + mux-clk-parent = <&pll 1>; >>>>> > >> > + baud-clk-rate = <460800>; >>> > > >>> > > This mixes patterns for references to clocks. Plus it requires composing >>> > > property names which is a little painful. I'd rather see a list of >>> > > tuples to match the existing pattern already in use >>> > > >>> > > clocks = <&clkcon 0>, <&clkcon 3>; >>> > > clock-names = "baud", "mux"; >>> > > clock-parents = <0> <&pll 1>; >>> > > clock-rates = <0> <460800>; >> > >> > Thank you for the review. This looks much better to me. My bad, I wasn't >> > aware 0 can be used to denote an empty phandle like this. ePAPR seems not >> > to be specifying exact meaning of the 'phandle' property values, except >> > they be unique. Anyway, it seems to be clearly documented within the >> > __of_parse_phandle_with_args() function. >> > >> > I'll try this modified binding instead, presumably it would be useful to >> > have a variant of __of_parse_phandle_with_args() function which would >> > accept a context data containing result of previous call within an iteration, >> > similarly as of_property_next_string() is written. So we don't iterate >> > from beginning of the list with each __of_parse_phandle_with_args() call. >> > But it's an optimization issue that could be considered separately I guess. > > I was always partial to the regulator style of blahblah-supply but > Grant's suggestion is much cleaner with respect to the rest of the clock > binding. I don't have a strong opinion, I'm slightly inclined towards Grant's suggestion, which doesn't have a problem of limiting effective clk name to 21 characters. Also DT property names with underscores coming from the clock names are a bit incorrect and it might be not immediately obvious which part of name is a canonical property's name and which is clock's name. Let's consider property names like: mux-clk-parent, divider-clk-rate, sclk_mmc0-clk-parent, sclk_uart_baud0-clk-parent, etc. > I guess it will be a bit ugly if a very long array is needed with a > sparse attribute. E.g. 20 clocks specified in the 'clocks' property and > only a single clock needs to have its parent or rate specified. It was also concerning me, but this inconvenience could be mitigated by reordering content of clocks/clock-names properties so that the clocks for which parents and/or rates are being assigned are first on the list. Then number of padding zeros is minimized. > Is there a reason not to support both methods? -- Regards, Sylwester -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sun, 23 Feb 2014 16:48:26 -0800, Mike Turquette <mturquette@linaro.org> wrote: > Quoting Sylwester Nawrocki (2014-02-21 02:38:21) > > On 20/02/14 15:09, Grant Likely wrote: > > [...] > > >> > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > > >> > index 7c52c29..d618498 100644 > > >> > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt > > >> > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > > >> > @@ -115,3 +115,27 @@ clock signal, and a UART. > > >> > ("pll" and "pll-switched"). > > >> > * The UART has its baud clock connected the external oscillator and its > > >> > register clock connected to the PLL clock (the "pll-switched" signal) > > >> > + > > >> > +==Static initial configuration of clock parent and clock frequency== > > >> > + > > >> > +Some platforms require static configuration of (parts of) the clock controller > > >> > +often determined by the board design. Such a configuration can be specified in > > >> > +a clock consumer node through [clk-name]-clk-parent and [clk-name]-clk-rate DT > > >> > +properties. The former should contain phandle and clock specifier of the parent > > >> > +clock, the latter the required clock's frequency value (one cell). "clk-name" > > >> > +should be listed in the clock-names property and a phandle and a clock specifier > > >> > +pair corresponding to it should be present in the clocks property. > > >> > + > > >> > + uart@a000 { > > >> > + compatible = "fsl,imx-uart"; > > >> > + reg = <0xa000 0x1000>; > > >> > + ... > > >> > + clocks = <&clkcon 0>, <&clkcon 3>; > > >> > + clock-names = "baud", "mux"; > > >> > + > > >> > + mux-clk-parent = <&pll 1>; > > >> > + baud-clk-rate = <460800>; > > > > > > This mixes patterns for references to clocks. Plus it requires composing > > > property names which is a little painful. I'd rather see a list of > > > tuples to match the existing pattern already in use > > > > > > clocks = <&clkcon 0>, <&clkcon 3>; > > > clock-names = "baud", "mux"; > > > clock-parents = <0> <&pll 1>; > > > clock-rates = <0> <460800>; > > > > Thank you for the review. This looks much better to me. My bad, I wasn't > > aware 0 can be used to denote an empty phandle like this. ePAPR seems not > > to be specifying exact meaning of the 'phandle' property values, except > > they be unique. Anyway, it seems to be clearly documented within the > > __of_parse_phandle_with_args() function. > > > > I'll try this modified binding instead, presumably it would be useful to > > have a variant of __of_parse_phandle_with_args() function which would > > accept a context data containing result of previous call within an iteration, > > similarly as of_property_next_string() is written. So we don't iterate > > from beginning of the list with each __of_parse_phandle_with_args() call. > > But it's an optimization issue that could be considered separately I guess. > > I was always partial to the regulator style of blahblah-supply but > Grant's suggestion is much cleaner with respect to the rest of the clock > binding. > > I guess it will be a bit ugly if a very long array is needed with a > sparse attribute. E.g. 20 clocks specified in the 'clocks' property and > only a single clock needs to have its parent or rate specified. > > Is there a reason not to support both methods? Yes. Complexity. Having two ways to do it is far worse to maintain. g. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 24 Feb 2014 19:11:18 +0100, Sylwester Nawrocki <s.nawrocki@samsung.com> wrote: > On 24/02/14 01:48, Mike Turquette wrote: > > Quoting Sylwester Nawrocki (2014-02-21 02:38:21) > >> > On 20/02/14 15:09, Grant Likely wrote: > >> > [...] > >>>>> > >> > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt > >>>>> > >> > index 7c52c29..d618498 100644 > >>>>> > >> > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt > >>>>> > >> > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt > >>>>> > >> > @@ -115,3 +115,27 @@ clock signal, and a UART. > >>>>> > >> > ("pll" and "pll-switched"). > >>>>> > >> > * The UART has its baud clock connected the external oscillator and its > >>>>> > >> > register clock connected to the PLL clock (the "pll-switched" signal) > >>>>> > >> > + > >>>>> > >> > +==Static initial configuration of clock parent and clock frequency== > >>>>> > >> > + > >>>>> > >> > +Some platforms require static configuration of (parts of) the clock controller > >>>>> > >> > +often determined by the board design. Such a configuration can be specified in > >>>>> > >> > +a clock consumer node through [clk-name]-clk-parent and [clk-name]-clk-rate DT > >>>>> > >> > +properties. The former should contain phandle and clock specifier of the parent > >>>>> > >> > +clock, the latter the required clock's frequency value (one cell). "clk-name" > >>>>> > >> > +should be listed in the clock-names property and a phandle and a clock specifier > >>>>> > >> > +pair corresponding to it should be present in the clocks property. > >>>>> > >> > + > >>>>> > >> > + uart@a000 { > >>>>> > >> > + compatible = "fsl,imx-uart"; > >>>>> > >> > + reg = <0xa000 0x1000>; > >>>>> > >> > + ... > >>>>> > >> > + clocks = <&clkcon 0>, <&clkcon 3>; > >>>>> > >> > + clock-names = "baud", "mux"; > >>>>> > >> > + > >>>>> > >> > + mux-clk-parent = <&pll 1>; > >>>>> > >> > + baud-clk-rate = <460800>; > >>> > > > >>> > > This mixes patterns for references to clocks. Plus it requires composing > >>> > > property names which is a little painful. I'd rather see a list of > >>> > > tuples to match the existing pattern already in use > >>> > > > >>> > > clocks = <&clkcon 0>, <&clkcon 3>; > >>> > > clock-names = "baud", "mux"; > >>> > > clock-parents = <0> <&pll 1>; > >>> > > clock-rates = <0> <460800>; > >> > > >> > Thank you for the review. This looks much better to me. My bad, I wasn't > >> > aware 0 can be used to denote an empty phandle like this. ePAPR seems not > >> > to be specifying exact meaning of the 'phandle' property values, except > >> > they be unique. Anyway, it seems to be clearly documented within the > >> > __of_parse_phandle_with_args() function. > >> > > >> > I'll try this modified binding instead, presumably it would be useful to > >> > have a variant of __of_parse_phandle_with_args() function which would > >> > accept a context data containing result of previous call within an iteration, > >> > similarly as of_property_next_string() is written. So we don't iterate > >> > from beginning of the list with each __of_parse_phandle_with_args() call. > >> > But it's an optimization issue that could be considered separately I guess. > > > > I was always partial to the regulator style of blahblah-supply but > > Grant's suggestion is much cleaner with respect to the rest of the clock > > binding. > > I don't have a strong opinion, I'm slightly inclined towards Grant's suggestion, > which doesn't have a problem of limiting effective clk name to 21 characters. > > Also DT property names with underscores coming from the clock names are a bit > incorrect and it might be not immediately obvious which part of name is a > canonical property's name and which is clock's name. Let's consider property > names like: > > mux-clk-parent, divider-clk-rate, sclk_mmc0-clk-parent, sclk_uart_baud0-clk-parent, > etc. > > > I guess it will be a bit ugly if a very long array is needed with a > > sparse attribute. E.g. 20 clocks specified in the 'clocks' property and > > only a single clock needs to have its parent or rate specified. > > It was also concerning me, but this inconvenience could be mitigated by > reordering content of clocks/clock-names properties so that the clocks for > which parents and/or rates are being assigned are first on the list. > Then number of padding zeros is minimized. If the array really gets that long for a device, then groups of clocks can also be split off into sub-nodes. g. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt index 7c52c29..d618498 100644 --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt @@ -115,3 +115,27 @@ clock signal, and a UART. ("pll" and "pll-switched"). * The UART has its baud clock connected the external oscillator and its register clock connected to the PLL clock (the "pll-switched" signal) + +==Static initial configuration of clock parent and clock frequency== + +Some platforms require static configuration of (parts of) the clock controller +often determined by the board design. Such a configuration can be specified in +a clock consumer node through [clk-name]-clk-parent and [clk-name]-clk-rate DT +properties. The former should contain phandle and clock specifier of the parent +clock, the latter the required clock's frequency value (one cell). "clk-name" +should be listed in the clock-names property and a phandle and a clock specifier +pair corresponding to it should be present in the clocks property. + + uart@a000 { + compatible = "fsl,imx-uart"; + reg = <0xa000 0x1000>; + ... + clocks = <&clkcon 0>, <&clkcon 3>; + clock-names = "baud", "mux"; + + mux-clk-parent = <&pll 1>; + baud-clk-rate = <460800>; + }; + +In this example the pll is set as parent of "mux" clock and frequency of "baud" +clock is specified as 460800 Hz. diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 19f6f3f..9238e08 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -19,6 +19,7 @@ #include <linux/of.h> #include <linux/device.h> #include <linux/init.h> +#include <linux/platform_device.h> #include <linux/sched.h> #include "clk.h" @@ -2527,6 +2528,97 @@ const char *of_clk_get_parent_name(struct device_node *np, int index) } EXPORT_SYMBOL_GPL(of_clk_get_parent_name); +static void __of_clk_assigned_config_set(struct clk *clk, struct clk *pclk, + u32 rate) +{ + int rc; + + if (rate) { + rc = clk_set_rate(clk, rate); + if (rc < 0) + pr_err("clk: couldn't set rate of clock %s (%d)\n", + __clk_get_name(clk), rc); + else + pr_debug("clk: set rate of clock %s to %u\n", + __clk_get_name(clk), rate); + } + + if (!IS_ERR(pclk)) { + rc = clk_set_parent(clk, pclk); + if (rc < 0) + pr_err("clk: couldn't set %s as parent of %s (%d)\n", + __clk_get_name(pclk), __clk_get_name(clk), rc); + else + pr_debug("clk: set %s as parent of %s\n", + __clk_get_name(pclk), __clk_get_name(clk)); + } +} + +static void of_clk_assigned_config_parse(struct device_node *node) +{ + char prop_name[OF_PROP_NAME_MAXLEN]; + struct property *prop; + const char *clk_name; + int rc, index = 0; + + of_property_for_each_string(node, "clock-names", prop, clk_name) { + struct clk *clk, *pclk; + u32 rate = 0; + + snprintf(prop_name, OF_PROP_NAME_MAXLEN, + "%s-clk-parent", clk_name); + pclk = of_clk_get_list_entry(node, prop_name, 0); + + snprintf(prop_name, OF_PROP_NAME_MAXLEN, + "%s-clk-rate", clk_name); + rc = of_property_read_u32(node, prop_name, &rate); + + if (!rc || !IS_ERR(pclk)) { + /* + * Assuming here of_property_for_each_string() returns + * consecutive values of a DT property in ascending + * index order. + */ + clk = of_clk_get(node, index); + + if (!IS_ERR(clk)) + __of_clk_assigned_config_set(clk, pclk, rate); + else + pr_err("clk: couldn't get clk %s\n", clk_name); + } + index++; + } +} + + +static int of_clk_setup_notifier_call(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct device *dev = data; + + if (!dev->of_node) + return NOTIFY_DONE; + + switch (event) { + case BUS_NOTIFY_BIND_DRIVER: + /* Parse and configure DT assigned clock parents and rates */ + of_clk_assigned_config_parse(dev->of_node); + break; + } + + return NOTIFY_DONE; +} + +static struct notifier_block of_clk_setup_nb = { + .notifier_call = of_clk_setup_notifier_call, +}; + +int __init of_clk_setup_notifier_init(void) +{ + return bus_register_notifier(&platform_bus_type, &of_clk_setup_nb); +} +subsys_initcall(of_clk_setup_notifier_init); + /** * of_clk_init() - Scan and init clock providers from the DT * @matches: array of compatible values and init functions for providers.