diff options
author | Boris BREZILLON <boris.brezillon@free-electrons.com> | 2014-05-15 10:55:11 +0200 |
---|---|---|
committer | Maxime Ripard <maxime.ripard@free-electrons.com> | 2014-06-11 10:25:02 +0200 |
commit | c8a76cac19eebf65f629e3676e57743f9dfeea8f (patch) | |
tree | 3988645d9fe86f15009e324b8e0ac575d2c27d7d /drivers/clk/sunxi/clk-sun6i-ar100.c | |
parent | efb3184c08927c54ed984c85f69f54ff1dbd2c37 (diff) |
clk: sunxi: add PRCM (Power/Reset/Clock Management) clks support
The PRCM (Power/Reset/Clock Management) unit provides several clock
devices:
- AR100 clk: used to clock the Power Management co-processor
- AHB0 clk: used to clock the AHB0 bus
- APB0 clk and gates: used to clk peripherals connected to the APB0 bus
Add support for these clks in a separate driver so that they can be probed
as platform devices instead of registered during early init.
This is needed to be able to probe PRCM MFD subdevices.
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Emilio López <emilio@elopez.com.ar>
Diffstat (limited to 'drivers/clk/sunxi/clk-sun6i-ar100.c')
-rw-r--r-- | drivers/clk/sunxi/clk-sun6i-ar100.c | 233 |
1 files changed, 233 insertions, 0 deletions
diff --git a/drivers/clk/sunxi/clk-sun6i-ar100.c b/drivers/clk/sunxi/clk-sun6i-ar100.c new file mode 100644 index 000000000000..f73cc051f0dd --- /dev/null +++ b/drivers/clk/sunxi/clk-sun6i-ar100.c @@ -0,0 +1,233 @@ +/* + * Copyright (C) 2014 Free Electrons + * + * License Terms: GNU General Public License v2 + * Author: Boris BREZILLON <boris.brezillon@free-electrons.com> + * + * Allwinner A31 AR100 clock driver + * + */ + +#include <linux/clk-provider.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/platform_device.h> + +#define SUN6I_AR100_MAX_PARENTS 4 +#define SUN6I_AR100_SHIFT_MASK 0x3 +#define SUN6I_AR100_SHIFT_MAX SUN6I_AR100_SHIFT_MASK +#define SUN6I_AR100_SHIFT_SHIFT 4 +#define SUN6I_AR100_DIV_MASK 0x1f +#define SUN6I_AR100_DIV_MAX (SUN6I_AR100_DIV_MASK + 1) +#define SUN6I_AR100_DIV_SHIFT 8 +#define SUN6I_AR100_MUX_MASK 0x3 +#define SUN6I_AR100_MUX_SHIFT 16 + +struct ar100_clk { + struct clk_hw hw; + void __iomem *reg; +}; + +static inline struct ar100_clk *to_ar100_clk(struct clk_hw *hw) +{ + return container_of(hw, struct ar100_clk, hw); +} + +static unsigned long ar100_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct ar100_clk *clk = to_ar100_clk(hw); + u32 val = readl(clk->reg); + int shift = (val >> SUN6I_AR100_SHIFT_SHIFT) & SUN6I_AR100_SHIFT_MASK; + int div = (val >> SUN6I_AR100_DIV_SHIFT) & SUN6I_AR100_DIV_MASK; + + return (parent_rate >> shift) / (div + 1); +} + +static long ar100_determine_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *best_parent_rate, + struct clk **best_parent_clk) +{ + int nparents = __clk_get_num_parents(hw->clk); + long best_rate = -EINVAL; + int i; + + *best_parent_clk = NULL; + + for (i = 0; i < nparents; i++) { + unsigned long parent_rate; + unsigned long tmp_rate; + struct clk *parent; + unsigned long div; + int shift; + + parent = clk_get_parent_by_index(hw->clk, i); + parent_rate = __clk_get_rate(parent); + div = DIV_ROUND_UP(parent_rate, rate); + + /* + * The AR100 clk contains 2 divisors: + * - one power of 2 divisor + * - one regular divisor + * + * First check if we can safely shift (or divide by a power + * of 2) without losing precision on the requested rate. + */ + shift = ffs(div) - 1; + if (shift > SUN6I_AR100_SHIFT_MAX) + shift = SUN6I_AR100_SHIFT_MAX; + + div >>= shift; + + /* + * Then if the divisor is still bigger than what the HW + * actually supports, use a bigger shift (or power of 2 + * divider) value and accept to lose some precision. + */ + while (div > SUN6I_AR100_DIV_MAX) { + shift++; + div >>= 1; + if (shift > SUN6I_AR100_SHIFT_MAX) + break; + } + + /* + * If the shift value (or power of 2 divider) is bigger + * than what the HW actually support, skip this parent. + */ + if (shift > SUN6I_AR100_SHIFT_MAX) + continue; + + tmp_rate = (parent_rate >> shift) / div; + if (!*best_parent_clk || tmp_rate > best_rate) { + *best_parent_clk = parent; + *best_parent_rate = parent_rate; + best_rate = tmp_rate; + } + } + + return best_rate; +} + +static int ar100_set_parent(struct clk_hw *hw, u8 index) +{ + struct ar100_clk *clk = to_ar100_clk(hw); + u32 val = readl(clk->reg); + + if (index >= SUN6I_AR100_MAX_PARENTS) + return -EINVAL; + + val &= ~(SUN6I_AR100_MUX_MASK << SUN6I_AR100_MUX_SHIFT); + val |= (index << SUN6I_AR100_MUX_SHIFT); + writel(val, clk->reg); + + return 0; +} + +static u8 ar100_get_parent(struct clk_hw *hw) +{ + struct ar100_clk *clk = to_ar100_clk(hw); + return (readl(clk->reg) >> SUN6I_AR100_MUX_SHIFT) & + SUN6I_AR100_MUX_MASK; +} + +static int ar100_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + unsigned long div = parent_rate / rate; + struct ar100_clk *clk = to_ar100_clk(hw); + u32 val = readl(clk->reg); + int shift; + + if (parent_rate % rate) + return -EINVAL; + + shift = ffs(div) - 1; + if (shift > SUN6I_AR100_SHIFT_MAX) + shift = SUN6I_AR100_SHIFT_MAX; + + div >>= shift; + + if (div > SUN6I_AR100_DIV_MAX) + return -EINVAL; + + val &= ~((SUN6I_AR100_SHIFT_MASK << SUN6I_AR100_SHIFT_SHIFT) | + (SUN6I_AR100_DIV_MASK << SUN6I_AR100_DIV_SHIFT)); + val |= (shift << SUN6I_AR100_SHIFT_SHIFT) | + (div << SUN6I_AR100_DIV_SHIFT); + writel(val, clk->reg); + + return 0; +} + +struct clk_ops ar100_ops = { + .recalc_rate = ar100_recalc_rate, + .determine_rate = ar100_determine_rate, + .set_parent = ar100_set_parent, + .get_parent = ar100_get_parent, + .set_rate = ar100_set_rate, +}; + +static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev) +{ + const char *parents[SUN6I_AR100_MAX_PARENTS]; + struct device_node *np = pdev->dev.of_node; + const char *clk_name = np->name; + struct clk_init_data init; + struct ar100_clk *ar100; + struct resource *r; + struct clk *clk; + int nparents; + int i; + + ar100 = devm_kzalloc(&pdev->dev, sizeof(*ar100), GFP_KERNEL); + if (!ar100) + return -ENOMEM; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + ar100->reg = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(ar100->reg)) + return PTR_ERR(ar100->reg); + + nparents = of_clk_get_parent_count(np); + if (nparents > SUN6I_AR100_MAX_PARENTS) + nparents = SUN6I_AR100_MAX_PARENTS; + + for (i = 0; i < nparents; i++) + parents[i] = of_clk_get_parent_name(np, i); + + of_property_read_string(np, "clock-output-names", &clk_name); + + init.name = clk_name; + init.ops = &ar100_ops; + init.parent_names = parents; + init.num_parents = nparents; + init.flags = 0; + + ar100->hw.init = &init; + + clk = clk_register(&pdev->dev, &ar100->hw); + if (IS_ERR(clk)) + return PTR_ERR(clk); + + return of_clk_add_provider(np, of_clk_src_simple_get, clk); +} + +const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = { + { .compatible = "allwinner,sun6i-a31-ar100-clk" }, + { /* sentinel */ } +}; + +static struct platform_driver sun6i_a31_ar100_clk_driver = { + .driver = { + .name = "sun6i-a31-ar100-clk", + .owner = THIS_MODULE, + .of_match_table = sun6i_a31_ar100_clk_dt_ids, + }, + .probe = sun6i_a31_ar100_clk_probe, +}; +module_platform_driver(sun6i_a31_ar100_clk_driver); + +MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>"); +MODULE_DESCRIPTION("Allwinner A31 AR100 clock Driver"); +MODULE_LICENSE("GPL v2"); |