diff options
Diffstat (limited to 'drivers/clk/meson/clk-dualdiv.c')
| -rw-r--r-- | drivers/clk/meson/clk-dualdiv.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/drivers/clk/meson/clk-dualdiv.c b/drivers/clk/meson/clk-dualdiv.c new file mode 100644 index 0000000000..feae49a8f6 --- /dev/null +++ b/drivers/clk/meson/clk-dualdiv.c @@ -0,0 +1,143 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2017 BayLibre, SAS + * Author: Neil Armstrong <narmstrong@baylibre.com> + * Author: Jerome Brunet <jbrunet@baylibre.com> + */ + +/* + * The AO Domain embeds a dual/divider to generate a more precise + * 32,768KHz clock for low-power suspend mode and CEC. + * ______ ______ + * | | | | + * | Div1 |-| Cnt1 | + * /|______| |______|\ + * -| ______ ______ X--> Out + * \| | | |/ + * | Div2 |-| Cnt2 | + * |______| |______| + * + * The dividing can be switched to single or dual, with a counter + * for each divider to set when the switching is done. + */ + +#include <linux/clk-provider.h> +#include <linux/module.h> + +#include "clk-regmap.h" +#include "clk-dualdiv.h" + +static inline struct meson_clk_dualdiv_data * +meson_clk_dualdiv_data(struct clk_regmap *clk) +{ + return (struct meson_clk_dualdiv_data *)clk->data; +} + +static unsigned long +__dualdiv_param_to_rate(unsigned long parent_rate, + const struct meson_clk_dualdiv_param *p) +{ + if (!p->dual) + return DIV_ROUND_CLOSEST(parent_rate, p->n1); + + return DIV_ROUND_CLOSEST(parent_rate * (p->m1 + p->m2), + p->n1 * p->m1 + p->n2 * p->m2); +} + +static unsigned long meson_clk_dualdiv_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_regmap *clk = to_clk_regmap(hw); + struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk); + struct meson_clk_dualdiv_param setting; + + setting.dual = meson_parm_read(clk->map, &dualdiv->dual); + setting.n1 = meson_parm_read(clk->map, &dualdiv->n1) + 1; + setting.m1 = meson_parm_read(clk->map, &dualdiv->m1) + 1; + setting.n2 = meson_parm_read(clk->map, &dualdiv->n2) + 1; + setting.m2 = meson_parm_read(clk->map, &dualdiv->m2) + 1; + + return __dualdiv_param_to_rate(parent_rate, &setting); +} + +static const struct meson_clk_dualdiv_param * +__dualdiv_get_setting(unsigned long rate, unsigned long parent_rate, + struct meson_clk_dualdiv_data *dualdiv) +{ + const struct meson_clk_dualdiv_param *table = dualdiv->table; + unsigned long best = 0, now = 0; + unsigned int i, best_i = 0; + + if (!table) + return NULL; + + for (i = 0; table[i].n1; i++) { + now = __dualdiv_param_to_rate(parent_rate, &table[i]); + + /* If we get an exact match, don't bother any further */ + if (now == rate) { + return &table[i]; + } else if (abs(now - rate) < abs(best - rate)) { + best = now; + best_i = i; + } + } + + return (struct meson_clk_dualdiv_param *)&table[best_i]; +} + +static int meson_clk_dualdiv_determine_rate(struct clk_hw *hw, + struct clk_rate_request *req) +{ + struct clk_regmap *clk = to_clk_regmap(hw); + struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk); + const struct meson_clk_dualdiv_param *setting; + + setting = __dualdiv_get_setting(req->rate, req->best_parent_rate, + dualdiv); + if (setting) + req->rate = __dualdiv_param_to_rate(req->best_parent_rate, + setting); + else + req->rate = meson_clk_dualdiv_recalc_rate(hw, + req->best_parent_rate); + + return 0; +} + +static int meson_clk_dualdiv_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_regmap *clk = to_clk_regmap(hw); + struct meson_clk_dualdiv_data *dualdiv = meson_clk_dualdiv_data(clk); + const struct meson_clk_dualdiv_param *setting = + __dualdiv_get_setting(rate, parent_rate, dualdiv); + + if (!setting) + return -EINVAL; + + meson_parm_write(clk->map, &dualdiv->dual, setting->dual); + meson_parm_write(clk->map, &dualdiv->n1, setting->n1 - 1); + meson_parm_write(clk->map, &dualdiv->m1, setting->m1 - 1); + meson_parm_write(clk->map, &dualdiv->n2, setting->n2 - 1); + meson_parm_write(clk->map, &dualdiv->m2, setting->m2 - 1); + + return 0; +} + +const struct clk_ops meson_clk_dualdiv_ops = { + .recalc_rate = meson_clk_dualdiv_recalc_rate, + .determine_rate = meson_clk_dualdiv_determine_rate, + .set_rate = meson_clk_dualdiv_set_rate, +}; +EXPORT_SYMBOL_GPL(meson_clk_dualdiv_ops); + +const struct clk_ops meson_clk_dualdiv_ro_ops = { + .recalc_rate = meson_clk_dualdiv_recalc_rate, +}; +EXPORT_SYMBOL_GPL(meson_clk_dualdiv_ro_ops); + +MODULE_DESCRIPTION("Amlogic dual divider driver"); +MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>"); +MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>"); +MODULE_LICENSE("GPL v2"); |