summaryrefslogtreecommitdiffstats
path: root/drivers/clk/meson/clk-pll.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/clk/meson/clk-pll.c')
-rw-r--r--drivers/clk/meson/clk-pll.c453
1 files changed, 453 insertions, 0 deletions
diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
new file mode 100644
index 000000000..9e55617bc
--- /dev/null
+++ b/drivers/clk/meson/clk-pll.c
@@ -0,0 +1,453 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ *
+ * Copyright (c) 2018 Baylibre, SAS.
+ * Author: Jerome Brunet <jbrunet@baylibre.com>
+ */
+
+/*
+ * In the most basic form, a Meson PLL is composed as follows:
+ *
+ * PLL
+ * +--------------------------------+
+ * | |
+ * | +--+ |
+ * in >>-----[ /N ]--->| | +-----+ |
+ * | | |------| DCO |---->> out
+ * | +--------->| | +--v--+ |
+ * | | +--+ | |
+ * | | | |
+ * | +--[ *(M + (F/Fmax) ]<--+ |
+ * | |
+ * +--------------------------------+
+ *
+ * out = in * (m + frac / frac_max) / n
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/rational.h>
+
+#include "clk-regmap.h"
+#include "clk-pll.h"
+
+static inline struct meson_clk_pll_data *
+meson_clk_pll_data(struct clk_regmap *clk)
+{
+ return (struct meson_clk_pll_data *)clk->data;
+}
+
+static int __pll_round_closest_mult(struct meson_clk_pll_data *pll)
+{
+ if ((pll->flags & CLK_MESON_PLL_ROUND_CLOSEST) &&
+ !MESON_PARM_APPLICABLE(&pll->frac))
+ return 1;
+
+ return 0;
+}
+
+static unsigned long __pll_params_to_rate(unsigned long parent_rate,
+ unsigned int m, unsigned int n,
+ unsigned int frac,
+ struct meson_clk_pll_data *pll)
+{
+ u64 rate = (u64)parent_rate * m;
+
+ if (frac && MESON_PARM_APPLICABLE(&pll->frac)) {
+ u64 frac_rate = (u64)parent_rate * frac;
+
+ rate += DIV_ROUND_UP_ULL(frac_rate,
+ (1 << pll->frac.width));
+ }
+
+ return DIV_ROUND_UP_ULL(rate, n);
+}
+
+static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+ unsigned int m, n, frac;
+
+ n = meson_parm_read(clk->map, &pll->n);
+
+ /*
+ * On some HW, N is set to zero on init. This value is invalid as
+ * it would result in a division by zero. The rate can't be
+ * calculated in this case
+ */
+ if (n == 0)
+ return 0;
+
+ m = meson_parm_read(clk->map, &pll->m);
+
+ frac = MESON_PARM_APPLICABLE(&pll->frac) ?
+ meson_parm_read(clk->map, &pll->frac) :
+ 0;
+
+ return __pll_params_to_rate(parent_rate, m, n, frac, pll);
+}
+
+static unsigned int __pll_params_with_frac(unsigned long rate,
+ unsigned long parent_rate,
+ unsigned int m,
+ unsigned int n,
+ struct meson_clk_pll_data *pll)
+{
+ unsigned int frac_max = (1 << pll->frac.width);
+ u64 val = (u64)rate * n;
+
+ /* Bail out if we are already over the requested rate */
+ if (rate < parent_rate * m / n)
+ return 0;
+
+ if (pll->flags & CLK_MESON_PLL_ROUND_CLOSEST)
+ val = DIV_ROUND_CLOSEST_ULL(val * frac_max, parent_rate);
+ else
+ val = div_u64(val * frac_max, parent_rate);
+
+ val -= m * frac_max;
+
+ return min((unsigned int)val, (frac_max - 1));
+}
+
+static bool meson_clk_pll_is_better(unsigned long rate,
+ unsigned long best,
+ unsigned long now,
+ struct meson_clk_pll_data *pll)
+{
+ if (__pll_round_closest_mult(pll)) {
+ /* Round Closest */
+ if (abs(now - rate) < abs(best - rate))
+ return true;
+ } else {
+ /* Round down */
+ if (now <= rate && best < now)
+ return true;
+ }
+
+ return false;
+}
+
+static int meson_clk_get_pll_table_index(unsigned int index,
+ unsigned int *m,
+ unsigned int *n,
+ struct meson_clk_pll_data *pll)
+{
+ if (!pll->table[index].n)
+ return -EINVAL;
+
+ *m = pll->table[index].m;
+ *n = pll->table[index].n;
+
+ return 0;
+}
+
+static unsigned int meson_clk_get_pll_range_m(unsigned long rate,
+ unsigned long parent_rate,
+ unsigned int n,
+ struct meson_clk_pll_data *pll)
+{
+ u64 val = (u64)rate * n;
+
+ if (__pll_round_closest_mult(pll))
+ return DIV_ROUND_CLOSEST_ULL(val, parent_rate);
+
+ return div_u64(val, parent_rate);
+}
+
+static int meson_clk_get_pll_range_index(unsigned long rate,
+ unsigned long parent_rate,
+ unsigned int index,
+ unsigned int *m,
+ unsigned int *n,
+ struct meson_clk_pll_data *pll)
+{
+ *n = index + 1;
+
+ /* Check the predivider range */
+ if (*n >= (1 << pll->n.width))
+ return -EINVAL;
+
+ if (*n == 1) {
+ /* Get the boundaries out the way */
+ if (rate <= pll->range->min * parent_rate) {
+ *m = pll->range->min;
+ return -ENODATA;
+ } else if (rate >= pll->range->max * parent_rate) {
+ *m = pll->range->max;
+ return -ENODATA;
+ }
+ }
+
+ *m = meson_clk_get_pll_range_m(rate, parent_rate, *n, pll);
+
+ /* the pre-divider gives a multiplier too big - stop */
+ if (*m >= (1 << pll->m.width))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int meson_clk_get_pll_get_index(unsigned long rate,
+ unsigned long parent_rate,
+ unsigned int index,
+ unsigned int *m,
+ unsigned int *n,
+ struct meson_clk_pll_data *pll)
+{
+ if (pll->range)
+ return meson_clk_get_pll_range_index(rate, parent_rate,
+ index, m, n, pll);
+ else if (pll->table)
+ return meson_clk_get_pll_table_index(index, m, n, pll);
+
+ return -EINVAL;
+}
+
+static int meson_clk_get_pll_settings(unsigned long rate,
+ unsigned long parent_rate,
+ unsigned int *best_m,
+ unsigned int *best_n,
+ struct meson_clk_pll_data *pll)
+{
+ unsigned long best = 0, now = 0;
+ unsigned int i, m, n;
+ int ret;
+
+ for (i = 0, ret = 0; !ret; i++) {
+ ret = meson_clk_get_pll_get_index(rate, parent_rate,
+ i, &m, &n, pll);
+ if (ret == -EINVAL)
+ break;
+
+ now = __pll_params_to_rate(parent_rate, m, n, 0, pll);
+ if (meson_clk_pll_is_better(rate, best, now, pll)) {
+ best = now;
+ *best_m = m;
+ *best_n = n;
+
+ if (now == rate)
+ break;
+ }
+ }
+
+ return best ? 0 : -EINVAL;
+}
+
+static int meson_clk_pll_determine_rate(struct clk_hw *hw,
+ struct clk_rate_request *req)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+ unsigned int m, n, frac;
+ unsigned long round;
+ int ret;
+
+ ret = meson_clk_get_pll_settings(req->rate, req->best_parent_rate,
+ &m, &n, pll);
+ if (ret)
+ return ret;
+
+ round = __pll_params_to_rate(req->best_parent_rate, m, n, 0, pll);
+
+ if (!MESON_PARM_APPLICABLE(&pll->frac) || req->rate == round) {
+ req->rate = round;
+ return 0;
+ }
+
+ /*
+ * The rate provided by the setting is not an exact match, let's
+ * try to improve the result using the fractional parameter
+ */
+ frac = __pll_params_with_frac(req->rate, req->best_parent_rate, m, n, pll);
+ req->rate = __pll_params_to_rate(req->best_parent_rate, m, n, frac, pll);
+
+ return 0;
+}
+
+static int meson_clk_pll_wait_lock(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+ int delay = 24000000;
+
+ do {
+ /* Is the clock locked now ? */
+ if (meson_parm_read(clk->map, &pll->l))
+ return 0;
+
+ delay--;
+ } while (delay > 0);
+
+ return -ETIMEDOUT;
+}
+
+static int meson_clk_pll_init(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+ if (pll->init_count) {
+ meson_parm_write(clk->map, &pll->rst, 1);
+ regmap_multi_reg_write(clk->map, pll->init_regs,
+ pll->init_count);
+ meson_parm_write(clk->map, &pll->rst, 0);
+ }
+
+ return 0;
+}
+
+static int meson_clk_pll_is_enabled(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+ if (meson_parm_read(clk->map, &pll->rst) ||
+ !meson_parm_read(clk->map, &pll->en) ||
+ !meson_parm_read(clk->map, &pll->l))
+ return 0;
+
+ return 1;
+}
+
+static int meson_clk_pcie_pll_enable(struct clk_hw *hw)
+{
+ meson_clk_pll_init(hw);
+
+ if (meson_clk_pll_wait_lock(hw))
+ return -EIO;
+
+ return 0;
+}
+
+static int meson_clk_pll_enable(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+ /* do nothing if the PLL is already enabled */
+ if (clk_hw_is_enabled(hw))
+ return 0;
+
+ /* Make sure the pll is in reset */
+ meson_parm_write(clk->map, &pll->rst, 1);
+
+ /* Enable the pll */
+ meson_parm_write(clk->map, &pll->en, 1);
+
+ /* Take the pll out reset */
+ meson_parm_write(clk->map, &pll->rst, 0);
+
+ if (meson_clk_pll_wait_lock(hw))
+ return -EIO;
+
+ return 0;
+}
+
+static void meson_clk_pll_disable(struct clk_hw *hw)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+ /* Put the pll is in reset */
+ meson_parm_write(clk->map, &pll->rst, 1);
+
+ /* Disable the pll */
+ meson_parm_write(clk->map, &pll->en, 0);
+}
+
+static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct clk_regmap *clk = to_clk_regmap(hw);
+ struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+ unsigned int enabled, m, n, frac = 0;
+ unsigned long old_rate;
+ int ret;
+
+ if (parent_rate == 0 || rate == 0)
+ return -EINVAL;
+
+ old_rate = clk_hw_get_rate(hw);
+
+ ret = meson_clk_get_pll_settings(rate, parent_rate, &m, &n, pll);
+ if (ret)
+ return ret;
+
+ enabled = meson_parm_read(clk->map, &pll->en);
+ if (enabled)
+ meson_clk_pll_disable(hw);
+
+ meson_parm_write(clk->map, &pll->n, n);
+ meson_parm_write(clk->map, &pll->m, m);
+
+ if (MESON_PARM_APPLICABLE(&pll->frac)) {
+ frac = __pll_params_with_frac(rate, parent_rate, m, n, pll);
+ meson_parm_write(clk->map, &pll->frac, frac);
+ }
+
+ /* If the pll is stopped, bail out now */
+ if (!enabled)
+ return 0;
+
+ ret = meson_clk_pll_enable(hw);
+ if (ret) {
+ pr_warn("%s: pll did not lock, trying to restore old rate %lu\n",
+ __func__, old_rate);
+ /*
+ * FIXME: Do we really need/want this HACK ?
+ * It looks unsafe. what happens if the clock gets into a
+ * broken state and we can't lock back on the old_rate ? Looks
+ * like an infinite recursion is possible
+ */
+ meson_clk_pll_set_rate(hw, old_rate, parent_rate);
+ }
+
+ return ret;
+}
+
+/*
+ * The Meson G12A PCIE PLL is fined tuned to deliver a very precise
+ * 100MHz reference clock for the PCIe Analog PHY, and thus requires
+ * a strict register sequence to enable the PLL.
+ * To simplify, re-use the _init() op to enable the PLL and keep
+ * the other ops except set_rate since the rate is fixed.
+ */
+const struct clk_ops meson_clk_pcie_pll_ops = {
+ .recalc_rate = meson_clk_pll_recalc_rate,
+ .determine_rate = meson_clk_pll_determine_rate,
+ .is_enabled = meson_clk_pll_is_enabled,
+ .enable = meson_clk_pcie_pll_enable,
+ .disable = meson_clk_pll_disable
+};
+EXPORT_SYMBOL_GPL(meson_clk_pcie_pll_ops);
+
+const struct clk_ops meson_clk_pll_ops = {
+ .init = meson_clk_pll_init,
+ .recalc_rate = meson_clk_pll_recalc_rate,
+ .determine_rate = meson_clk_pll_determine_rate,
+ .set_rate = meson_clk_pll_set_rate,
+ .is_enabled = meson_clk_pll_is_enabled,
+ .enable = meson_clk_pll_enable,
+ .disable = meson_clk_pll_disable
+};
+EXPORT_SYMBOL_GPL(meson_clk_pll_ops);
+
+const struct clk_ops meson_clk_pll_ro_ops = {
+ .recalc_rate = meson_clk_pll_recalc_rate,
+ .is_enabled = meson_clk_pll_is_enabled,
+};
+EXPORT_SYMBOL_GPL(meson_clk_pll_ro_ops);
+
+MODULE_DESCRIPTION("Amlogic PLL driver");
+MODULE_AUTHOR("Carlo Caione <carlo@endlessm.com>");
+MODULE_AUTHOR("Jerome Brunet <jbrunet@baylibre.com>");
+MODULE_LICENSE("GPL v2");