diff options
Diffstat (limited to 'drivers/clk/bcm/clk-bcm53573-ilp.c')
| -rw-r--r-- | drivers/clk/bcm/clk-bcm53573-ilp.c | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/drivers/clk/bcm/clk-bcm53573-ilp.c b/drivers/clk/bcm/clk-bcm53573-ilp.c new file mode 100644 index 000000000..36eb3716f --- /dev/null +++ b/drivers/clk/bcm/clk-bcm53573-ilp.c @@ -0,0 +1,148 @@ +/* + * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/clk-provider.h> +#include <linux/err.h> +#include <linux/io.h> +#include <linux/mfd/syscon.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/regmap.h> +#include <linux/slab.h> + +#define PMU_XTAL_FREQ_RATIO 0x66c +#define XTAL_ALP_PER_4ILP 0x00001fff +#define XTAL_CTL_EN 0x80000000 +#define PMU_SLOW_CLK_PERIOD 0x6dc + +struct bcm53573_ilp { + struct clk_hw hw; + struct regmap *regmap; +}; + +static int bcm53573_ilp_enable(struct clk_hw *hw) +{ + struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw); + + regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0x10199); + regmap_write(ilp->regmap, 0x674, 0x10000); + + return 0; +} + +static void bcm53573_ilp_disable(struct clk_hw *hw) +{ + struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw); + + regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0); + regmap_write(ilp->regmap, 0x674, 0); +} + +static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw); + struct regmap *regmap = ilp->regmap; + u32 last_val, cur_val; + int sum = 0, num = 0, loop_num = 0; + int avg; + + /* Enable measurement */ + regmap_write(regmap, PMU_XTAL_FREQ_RATIO, XTAL_CTL_EN); + + /* Read initial value */ + regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &last_val); + last_val &= XTAL_ALP_PER_4ILP; + + /* + * At minimum we should loop for a bit to let hardware do the + * measurement. This isn't very accurate however, so for a better + * precision lets try getting 20 different values for and use average. + */ + while (num < 20) { + regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &cur_val); + cur_val &= XTAL_ALP_PER_4ILP; + + if (cur_val != last_val) { + /* Got different value, use it */ + sum += cur_val; + num++; + loop_num = 0; + last_val = cur_val; + } else if (++loop_num > 5000) { + /* Same value over and over, give up */ + sum += cur_val; + num++; + break; + } + + cpu_relax(); + } + + /* Disable measurement to save power */ + regmap_write(regmap, PMU_XTAL_FREQ_RATIO, 0x0); + + avg = sum / num; + + return parent_rate * 4 / avg; +} + +static const struct clk_ops bcm53573_ilp_clk_ops = { + .enable = bcm53573_ilp_enable, + .disable = bcm53573_ilp_disable, + .recalc_rate = bcm53573_ilp_recalc_rate, +}; + +static void bcm53573_ilp_init(struct device_node *np) +{ + struct bcm53573_ilp *ilp; + struct clk_init_data init = { }; + const char *parent_name; + int err; + + ilp = kzalloc(sizeof(*ilp), GFP_KERNEL); + if (!ilp) + return; + + parent_name = of_clk_get_parent_name(np, 0); + if (!parent_name) { + err = -ENOENT; + goto err_free_ilp; + } + + ilp->regmap = syscon_node_to_regmap(of_get_parent(np)); + if (IS_ERR(ilp->regmap)) { + err = PTR_ERR(ilp->regmap); + goto err_free_ilp; + } + + init.name = np->name; + init.ops = &bcm53573_ilp_clk_ops; + init.parent_names = &parent_name; + init.num_parents = 1; + + ilp->hw.init = &init; + err = clk_hw_register(NULL, &ilp->hw); + if (err) + goto err_free_ilp; + + err = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &ilp->hw); + if (err) + goto err_clk_hw_unregister; + + return; + +err_clk_hw_unregister: + clk_hw_unregister(&ilp->hw); +err_free_ilp: + kfree(ilp); + pr_err("Failed to init ILP clock: %d\n", err); +} + +/* We need it very early for arch code, before device model gets ready */ +CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init); |