Re: [PATCH v4 3/5] clk: sunxi: Add sun9i A80 cpus (cpu special) clock support

Rob Herring
2015-11-30T17:13:25Z

On Sun, Nov 29, 2015 at 11:03:08AM +0800, Chen-Yu Tsai wrote:
> The "cpus" clock is the clock for the embedded processor in the A80.
> It is also part of the PRCM clock tree. This clock includes a pre-
> divider on one of its inputs. For now we are using a custom clock
> driver for it. In the future we may want to develop a generalized
> driver for these types of clocks, which also includes the AHB clock
> driver on sun[5678]i.
>
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>
> ---
> Documentation/devicetree/bindings/clock/sunxi.txt | 1 +

For the binding:

Acked-by: Rob Herring <robh@kernel.org>

> drivers/clk/sunxi/Makefile | 1 +
> drivers/clk/sunxi/clk-sun9i-cpus.c | 240 ++++++++++++++++++++++
> 3 files changed, 242 insertions(+)
> create mode 100644 drivers/clk/sunxi/clk-sun9i-cpus.c
>
> diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
> index b6859ed6913f..153ac72869e8 100644
> --- a/Documentation/devicetree/bindings/clock/sunxi.txt
> +++ b/Documentation/devicetree/bindings/clock/sunxi.txt
> @@ -27,6 +27,7 @@ Required properties:
> "allwinner,sun5i-a10s-ahb-gates-clk" - for the AHB gates on A10s
> "allwinner,sun7i-a20-ahb-gates-clk" - for the AHB gates on A20
> "allwinner,sun6i-a31-ar100-clk" - for the AR100 on A31
> + "allwinner,sun9i-a80-cpus-clk" - for the CPUS on A80
> "allwinner,sun6i-a31-ahb1-clk" - for the AHB1 clock on A31
> "allwinner,sun6i-a31-ahb1-gates-clk" - for the AHB1 gates on A31
> "allwinner,sun8i-a23-ahb1-gates-clk" - for the AHB1 gates on A23
> diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
> index c55d5cd1c0e5..f7d439fa9980 100644
> --- a/drivers/clk/sunxi/Makefile
> +++ b/drivers/clk/sunxi/Makefile
> @@ -16,6 +16,7 @@ obj-y += clk-sun9i-mmc.o
> obj-y += clk-usb.o
>
> obj-$(CONFIG_MACH_SUN9I) += clk-sun8i-apb0.o
> +obj-$(CONFIG_MACH_SUN9I) += clk-sun9i-cpus.o
>
> obj-$(CONFIG_MFD_SUN6I_PRCM) += \
> clk-sun6i-ar100.o clk-sun6i-apb0.o clk-sun6i-apb0-gates.o
> diff --git a/drivers/clk/sunxi/clk-sun9i-cpus.c b/drivers/clk/sunxi/clk-sun9i-cpus.c
> new file mode 100644
> index 000000000000..7626d2194b96
> --- /dev/null
> +++ b/drivers/clk/sunxi/clk-sun9i-cpus.c
> @@ -0,0 +1,240 @@
> +/*
> + * Copyright (C) 2015 Chen-Yu Tsai
> + *
> + * Chen-Yu Tsai <wens@csie.org>
> + *
> + * Allwinner A80 CPUS clock driver
> + *
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clk-provider.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +
> +static DEFINE_SPINLOCK(sun9i_a80_cpus_lock);
> +
> +/**
> + * sun9i_a80_cpus_clk_setup() - Setup function for a80 cpus composite clk
> + */
> +
> +#define SUN9I_CPUS_MAX_PARENTS 4
> +#define SUN9I_CPUS_MUX_PARENT_PLL4 3
> +#define SUN9I_CPUS_MUX_SHIFT 16
> +#define SUN9I_CPUS_MUX_MASK GENMASK(17, 16)
> +#define SUN9I_CPUS_MUX_GET_PARENT(reg) ((reg & SUN9I_CPUS_MUX_MASK) >> \
> + SUN9I_CPUS_MUX_SHIFT)
> +
> +#define SUN9I_CPUS_DIV_SHIFT 4
> +#define SUN9I_CPUS_DIV_MASK GENMASK(5, 4)
> +#define SUN9I_CPUS_DIV_GET(reg) ((reg & SUN9I_CPUS_DIV_MASK) >> \
> + SUN9I_CPUS_DIV_SHIFT)
> +#define SUN9I_CPUS_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_DIV_MASK) | \
> + (div << SUN9I_CPUS_DIV_SHIFT))
> +#define SUN9I_CPUS_PLL4_DIV_SHIFT 8
> +#define SUN9I_CPUS_PLL4_DIV_MASK GENMASK(12, 8)
> +#define SUN9I_CPUS_PLL4_DIV_GET(reg) ((reg & SUN9I_CPUS_PLL4_DIV_MASK) >> \
> + SUN9I_CPUS_PLL4_DIV_SHIFT)
> +#define SUN9I_CPUS_PLL4_DIV_SET(reg, div) ((reg & ~SUN9I_CPUS_PLL4_DIV_MASK) | \
> + (div << SUN9I_CPUS_PLL4_DIV_SHIFT))
> +
> +struct sun9i_a80_cpus_clk {
> + struct clk_hw hw;
> + void __iomem *reg;
> +};
> +
> +#define to_sun9i_a80_cpus_clk(_hw) container_of(_hw, struct sun9i_a80_cpus_clk, hw)
> +
> +static unsigned long sun9i_a80_cpus_clk_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw);
> + unsigned long rate;
> + u32 reg;
> +
> + /* Fetch the register value */
> + reg = readl(cpus->reg);
> +
> + /* apply pre-divider first if parent is pll4 */
> + if (SUN9I_CPUS_MUX_GET_PARENT(reg) == SUN9I_CPUS_MUX_PARENT_PLL4)
> + parent_rate /= SUN9I_CPUS_PLL4_DIV_GET(reg) + 1;
> +
> + /* clk divider */
> + rate = parent_rate / (SUN9I_CPUS_DIV_GET(reg) + 1);
> +
> + return rate;
> +}
> +
> +static long sun9i_a80_cpus_clk_round(unsigned long rate, u8 *divp, u8 *pre_divp,
> + u8 parent, unsigned long parent_rate)
> +{
> + u8 div, pre_div = 1;
> +
> + /*
> + * clock can only divide, so we will never be able to achieve
> + * frequencies higher than the parent frequency
> + */
> + if (parent_rate && rate > parent_rate)
> + rate = parent_rate;
> +
> + div = DIV_ROUND_UP(parent_rate, rate);
> +
> + /* calculate pre-divider if parent is pll4 */
> + if (parent == SUN9I_CPUS_MUX_PARENT_PLL4 && div > 4) {
> + /* pre-divider is 1 ~ 32 */
> + if (div < 32) {
> + pre_div = div;
> + div = 1;
> + } else if (div < 64) {
> + pre_div = DIV_ROUND_UP(div, 2);
> + div = 2;
> + } else if (div < 96) {
> + pre_div = DIV_ROUND_UP(div, 3);
> + div = 3;
> + } else {
> + pre_div = DIV_ROUND_UP(div, 4);
> + div = 4;
> + }
> + }
> +
> + /* we were asked to pass back divider values */
> + if (divp) {
> + *divp = div - 1;
> + *pre_divp = pre_div - 1;
> + }
> +
> + return parent_rate / pre_div / div;
> +}
> +
> +static int sun9i_a80_cpus_clk_determine_rate(struct clk_hw *clk,
> + struct clk_rate_request *req)
> +{
> + struct clk_hw *parent, *best_parent = NULL;
> + int i, num_parents;
> + unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0;
> + unsigned long rate = req->rate;
> +
> + /* find the parent that can help provide the fastest rate <= rate */
> + num_parents = clk_hw_get_num_parents(clk);
> + for (i = 0; i < num_parents; i++) {
> + parent = clk_hw_get_parent_by_index(clk, i);
> + if (!parent)
> + continue;
> + if (clk_hw_get_flags(clk) & CLK_SET_RATE_PARENT)
> + parent_rate = clk_hw_round_rate(parent, rate);
> + else
> + parent_rate = clk_hw_get_rate(parent);
> +
> + child_rate = sun9i_a80_cpus_clk_round(rate, NULL, NULL, i,
> + parent_rate);
> +
> + if (child_rate <= rate && child_rate > best_child_rate) {
> + best_parent = parent;
> + best = parent_rate;
> + best_child_rate = child_rate;
> + }
> + }
> +
> + if (!best_parent)
> + return -EINVAL;
> +
> + req->best_parent_hw = best_parent;
> + req->best_parent_rate = best;
> + req->rate = best_child_rate;
> +
> + return 0;
> +}
> +
> +static int sun9i_a80_cpus_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct sun9i_a80_cpus_clk *cpus = to_sun9i_a80_cpus_clk(hw);
> + unsigned long flags;
> + u8 div, pre_div, parent;
> + u32 reg;
> +
> + spin_lock_irqsave(&sun9i_a80_cpus_lock, flags);
> +
> + reg = readl(cpus->reg);
> +
> + /* need to know which parent is used to apply pre-divider */
> + parent = SUN9I_CPUS_MUX_GET_PARENT(reg);
> + sun9i_a80_cpus_clk_round(rate, &div, &pre_div, parent, parent_rate);
> +
> + reg = SUN9I_CPUS_DIV_SET(reg, div);
> + reg = SUN9I_CPUS_PLL4_DIV_SET(reg, pre_div);
> + writel(reg, cpus->reg);
> +
> + spin_unlock_irqrestore(&sun9i_a80_cpus_lock, flags);
> +
> + return 0;
> +}
> +
> +static const struct clk_ops sun9i_a80_cpus_clk_ops = {
> + .determine_rate = sun9i_a80_cpus_clk_determine_rate,
> + .recalc_rate = sun9i_a80_cpus_clk_recalc_rate,
> + .set_rate = sun9i_a80_cpus_clk_set_rate,
> +};
> +
> +static void sun9i_a80_cpus_setup(struct device_node *node)
> +{
> + const char *clk_name = node->name;
> + const char *parents[SUN9I_CPUS_MAX_PARENTS];
> + struct resource res;
> + struct sun9i_a80_cpus_clk *cpus;
> + struct clk_mux *mux;
> + struct clk *clk;
> + int ret;
> +
> + cpus = kzalloc(sizeof(*cpus), GFP_KERNEL);
> + if (!cpus)
> + return;
> +
> + cpus->reg = of_io_request_and_map(node, 0, of_node_full_name(node));
> + if (IS_ERR(cpus->reg))
> + goto err_free_cpus;
> +
> + of_property_read_string(node, "clock-output-names", &clk_name);
> +
> + /* we have a mux, we will have >1 parents */
> + ret = of_clk_parent_fill(node, parents, SUN9I_CPUS_MAX_PARENTS);
> +
> + mux = kzalloc(sizeof(*mux), GFP_KERNEL);
> + if (!mux)
> + goto err_unmap;
> +
> + /* set up clock properties */
> + mux->reg = cpus->reg;
> + mux->shift = SUN9I_CPUS_MUX_SHIFT;
> + /* un-shifted mask is what mux_clk expects */
> + mux->mask = SUN9I_CPUS_MUX_MASK >> SUN9I_CPUS_MUX_SHIFT;
> + mux->lock = &sun9i_a80_cpus_lock;
> +
> + clk = clk_register_composite(NULL, clk_name, parents, ret,
> + &mux->hw, &clk_mux_ops,
> + &cpus->hw, &sun9i_a80_cpus_clk_ops,
> + NULL, NULL, 0);
> + if (IS_ERR(clk))
> + goto err_free_mux;
> +
> + ret = of_clk_add_provider(node, of_clk_src_simple_get, clk);
> + if (ret)
> + goto err_unregister;
> +
> + return;
> +
> +err_unregister:
> + clk_unregister(clk);
> +err_free_mux:
> + kfree(mux);
> +err_unmap:
> + iounmap(cpus->reg);
> + of_address_to_resource(node, 0, &res);
> + release_mem_region(res.start, resource_size(&res));
> +err_free_cpus:
> + kfree(cpus);
> +}
> +CLK_OF_DECLARE(sun9i_a80_cpus, "allwinner,sun9i-a80-cpus-clk",
> + sun9i_a80_cpus_setup);
> --
> 2.6.2
>