On 07/12/2012 02:15 AM, Sebastian Hesselbarth wrote: > As Rob's clock binding support patch is now up on clk-next, I'd like to > draw attention on this patch again. > -- > This patch adds support for using clock gates (clk-gate) from DT based > on Rob Herrings DT clk binding support for 3.6. > > It adds a helper function to clk-gate to allocate all resources required by > a set of individual clock gates, i.e. register base address and lock. Each > clock gate is described as a child of the clock-gating-control in DT and > also created by the helper function. > > Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxxxxxxx> > Cc: Grant Likely <grant.likely@xxxxxxxxxxxx> > Cc: Rob Herring <rob.herring@xxxxxxxxxxx> > Cc: Rob Landley <rob@xxxxxxxxxxx> > Cc: Mike Turquette <mturquette@xxxxxx> > Cc: devicetree-discuss@xxxxxxxxxxxxxxxx > Cc: linux-doc@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > --- > .../bindings/clock/clock-gating-control.txt | 80 > +++++++++++++++++++ > drivers/clk/clk-gate.c | 84 > ++++++++++++++++++++ > include/linux/clk-provider.h | 2 + > 3 files changed, 166 insertions(+) > create mode 100644 > Documentation/devicetree/bindings/clock/clock-gating-control.txt > > diff --git > a/Documentation/devicetree/bindings/clock/clock-gating-control.txt > b/Documentation/devicetree/bindings/clock/clock-gating-control.txt > new file mode 100644 > index 0000000..05f5728 > --- /dev/null > +++ b/Documentation/devicetree/bindings/clock/clock-gating-control.txt > @@ -0,0 +1,80 @@ > +Binding for simple clock gating control based on clock gate register > with one > +bit per clock gate. This is a clock consumer and also a clock provider > for a > +set of gated clocks that are described as children of this node. Each > clock gate > +is described by a bit number and polarity to control the gate. > + > +This binding uses the common clock binding[1]. > + > +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt > + > +==Clock gating control== > + > +Required properties: > +- compatible : shall be "clock-gating-control". > +- reg : should contain the register physical address and length for > + the clock gating control. > +- clocks : shared parent clock for all gated clocks. > +- #clock-cells : from common clock binding; shall be set to 0. > +- #address-cells : number of cells required to describe a clock gate; > + should be <2>. > +- #size-cells : should be zero. > + > +Each individual clock gate bit is described as a child of the > +corresponding gating control register with the following properties. > + > +Required child properties: > +- reg : should contain the individual bit and polarity to control > + the clock gate. A polarity of 0 means that by setting the > + bit to 1 the clock passes through the clock gate while > + setting the bit to 0 disables the clock. Any other value > + for polarity inverts the meaning of the control bit. This is a bit of overloading reg to specify the polarity. > + > +Optional child properties: > +- clocks : overrides the shared parent clock for this clock gate > + by the clock passed in this property. > +- clock-output-names : from common clock binding; allows to set > + a specific name for the gated clock output. > + > +==Example== > + > + /* fixed root clock */ > + osc: oscillator { > + compatible = "fixed-clock"; > + #clock-cells = <0>; > + clock-frequency = <166666667>; > + }; > + > + /* sata peripheral clock */ > + sata_clk: ext-oscillator { > + compatible = "fixed-clock"; > + #clock-cells = <0>; > + clock-frequency = <25000000>; > + }; > + > + /* register-based clock gating control */ > + gating-control@f10d0038 { > + compatible = "clock-gating-control"; > + reg = <0xf10d0038 0x4>; > + clocks = <&osc>; > + #clock-cells = <0>; > + #address-cells = <2>; > + #size-cells = <0>; > + > + /* USB0 clock gate on register bit 0 with inverted polarity */ > + cg_usb0: clockgate@0 { > + reg = <0 1>; /* register bit 0, inverted polarity */ > + }; > + > + /* PCIe0 clock gate on register bit 1 with normal polarity > + * and named output clock */ > + cg_pcie0: clockgate@1 { > + reg = <1 0>; /* register bit 1, normal polarity */ > + clock-output-names = "pcie0_clk"; > + }; > + > + /* SATA clock gate with different parent clock */ > + cg_sata: clockgate@3 { > + reg = <3 0>; /* register bit 3, normal polarity */ > + clocks = <&sata_clk>; > + }; I'm not sure I like the node per bit. What about a bit mask for valid bits and polarities. Then add a clock cell to specify the bit or index. i.MX has 2-bit enable fields for its leaf clocks, so how and if you would support that is something to think about. Rob > + }; > diff --git a/drivers/clk/clk-gate.c b/drivers/clk/clk-gate.c > index 578465e..1e88907 100644 > --- a/drivers/clk/clk-gate.c > +++ b/drivers/clk/clk-gate.c > @@ -15,6 +15,9 @@ > #include <linux/io.h> > #include <linux/err.h> > #include <linux/string.h> > +#include <linux/of.h> > +#include <linux/of_address.h> > +#include <linux/of_platform.h> > /** > * DOC: basic gatable clock which can gate and ungate it's ouput > @@ -148,3 +151,84 @@ struct clk *clk_register_gate(struct device *dev, > const char *name, > return clk; > } > + > +#ifdef CONFIG_OF > +/** > + * of_clock_gating_control_setup() - Setup function for clock gate control > + * This is a helper for using clk-gate from OF device tree. It allocates > + * a common lock for a base register and creates the individual > clk-gates. > + */ > +void __init of_clock_gating_control_setup(struct device_node *np) > +{ > + struct device_node *child; > + const char *pclk_name; > + void __iomem *base; > + spinlock_t *lockp; > + unsigned int rnum; > + u64 addr; > + > + pclk_name = of_clk_get_parent_name(np, 0); > + if (!pclk_name) { > + pr_debug("%s: unable to get parent clock for %s\n", > + __func__, np->full_name); > + return; > + } > + > + lockp = kzalloc(sizeof(spinlock_t), GFP_KERNEL); > + if (!lockp) { > + pr_debug("%s: unable to allocate spinlock for %s\n", > + __func__, np->full_name); > + return; > + } > + > + spin_lock_init(lockp); > + base = of_iomap(np, 0); > + rnum = sizeof(resource_size_t) * 8; > + addr = of_translate_address(np, of_get_property(np, "reg", NULL)); > + > + pr_debug("create clock gate control %s\n", np->full_name); > + > + for_each_child_of_node(np, child) { > + struct clk *cg; > + const char *cg_name; > + const char *cg_pclk_name; > + u32 propval[2]; > + unsigned int rbit; > + > + if (of_property_read_u32_array(child, "reg", propval, 2)) { > + pr_debug("%s: wrong #reg on %s\n", > + __func__, child->full_name); > + continue; > + } > + > + rbit = propval[0]; > + if (rbit >= rnum) { > + pr_debug("%s: bit position of %s exceeds resources\n", > + __func__, child->full_name); > + continue; > + } > + > + cg_pclk_name = of_clk_get_parent_name(child, 0); > + if (!pclk_name) > + cg_pclk_name = pclk_name; > + > + if (of_property_read_string(child, "clock-output-names", > + &cg_name)) { > + unsigned int nlen = 4 + 16 + strlen(child->name); > + char *name = kzalloc(nlen+1, GFP_KERNEL); > + if (!name) > + continue; > + snprintf(name, nlen, "%u@%llx.%s", rbit, > + (unsigned long long)addr, child->name); > + cg_name = name; > + } > + > + pr_debug(" create clock gate: %s\n", cg_name); > + > + cg = clk_register_gate(NULL, cg_name, cg_pclk_name, 0, > + base, rbit, propval[1], lockp); > + if (cg) > + of_clk_add_provider(child, of_clk_src_simple_get, cg); > + } > +} > +#endif > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h > index b97f61e..499eac2 100644 > --- a/include/linux/clk-provider.h > +++ b/include/linux/clk-provider.h > @@ -205,6 +205,8 @@ struct clk *clk_register_gate(struct device *dev, > const char *name, > void __iomem *reg, u8 bit_idx, > u8 clk_gate_flags, spinlock_t *lock); > +void of_clock_gating_control_setup(struct device_node *np); > + > /** > * struct clk_divider - adjustable divider clock > * -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html