summaryrefslogtreecommitdiffstats
path: root/drivers/clk/meson/clk-dualdiv.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/clk/meson/clk-dualdiv.c')
-rw-r--r--drivers/clk/meson/clk-dualdiv.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/drivers/clk/meson/clk-dualdiv.c b/drivers/clk/meson/clk-dualdiv.c
new file mode 100644
index 000000000..c5ca23a5e
--- /dev/null
+++ b/drivers/clk/meson/clk-dualdiv.c
@@ -0,0 +1,138 @@
+// 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 long meson_clk_dualdiv_round_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 meson_clk_dualdiv_recalc_rate(hw, *parent_rate);
+
+ return __dualdiv_param_to_rate(*parent_rate, setting);
+}
+
+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,
+ .round_rate = meson_clk_dualdiv_round_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");