--- /dev/null
+/*
+ * Copyright (c) 2015 Endless Mobile, Inc.
+ * Author: Carlo Caione <carlo@endlessm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*
+ * In the most basic form, a Meson PLL is composed as follows:
+ *
+ * PLL
+ * +------------------------------+
+ * | |
+ * in -----[ /N ]---[ *M ]---[ >>OD ]----->> out
+ * | ^ ^ |
+ * +------------------------------+
+ * | |
+ * FREF VCO
+ *
+ * out = (in * M / N) >> OD
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include "clkc.h"
+
+#define MESON_PLL_RESET BIT(29)
+#define MESON_PLL_LOCK BIT(31)
+
+struct meson_clk_pll {
+ struct clk_hw hw;
+ void __iomem *base;
+ struct pll_conf *conf;
+ unsigned int rate_count;
+ spinlock_t *lock;
+};
+#define to_meson_clk_pll(_hw) container_of(_hw, struct meson_clk_pll, hw)
+
+static unsigned long meson_clk_pll_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct meson_clk_pll *pll = to_meson_clk_pll(hw);
+ struct parm *p;
+ unsigned long parent_rate_mhz = parent_rate / 1000000;
+ unsigned long rate_mhz;
+ u16 n, m, od;
+ u32 reg;
+
+ p = &pll->conf->n;
+ reg = readl(pll->base + p->reg_off);
+ n = PARM_GET(p->width, p->shift, reg);
+
+ p = &pll->conf->m;
+ reg = readl(pll->base + p->reg_off);
+ m = PARM_GET(p->width, p->shift, reg);
+
+ p = &pll->conf->od;
+ reg = readl(pll->base + p->reg_off);
+ od = PARM_GET(p->width, p->shift, reg);
+
+ rate_mhz = (parent_rate_mhz * m / n) >> od;
+
+ return rate_mhz * 1000000;
+}
+
+static long meson_clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ struct meson_clk_pll *pll = to_meson_clk_pll(hw);
+ const struct pll_rate_table *rate_table = pll->conf->rate_table;
+ int i;
+
+ for (i = 0; i < pll->rate_count; i++) {
+ if (rate <= rate_table[i].rate)
+ return rate_table[i].rate;
+ }
+
+ /* else return the smallest value */
+ return rate_table[0].rate;
+}
+
+static const struct pll_rate_table *meson_clk_get_pll_settings(struct meson_clk_pll *pll,
+ unsigned long rate)
+{
+ const struct pll_rate_table *rate_table = pll->conf->rate_table;
+ int i;
+
+ for (i = 0; i < pll->rate_count; i++) {
+ if (rate == rate_table[i].rate)
+ return &rate_table[i];
+ }
+ return NULL;
+}
+
+static int meson_clk_pll_wait_lock(struct meson_clk_pll *pll,
+ struct parm *p_n)
+{
+ int delay = 24000000;
+ u32 reg;
+
+ while (delay > 0) {
+ reg = readl(pll->base + p_n->reg_off);
+
+ if (reg & MESON_PLL_LOCK)
+ return 0;
+ delay--;
+ }
+ return -ETIMEDOUT;
+}
+
+static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct meson_clk_pll *pll = to_meson_clk_pll(hw);
+ struct parm *p;
+ const struct pll_rate_table *rate_set;
+ unsigned long old_rate;
+ int ret = 0;
+ u32 reg;
+
+ if (parent_rate == 0 || rate == 0)
+ return -EINVAL;
+
+ old_rate = rate;
+
+ rate_set = meson_clk_get_pll_settings(pll, rate);
+ if (!rate_set)
+ return -EINVAL;
+
+ /* PLL reset */
+ p = &pll->conf->n;
+ reg = readl(pll->base + p->reg_off);
+ writel(reg | MESON_PLL_RESET, pll->base + p->reg_off);
+
+ reg = PARM_SET(p->width, p->shift, reg, rate_set->n);
+ writel(reg, pll->base + p->reg_off);
+
+ p = &pll->conf->m;
+ reg = readl(pll->base + p->reg_off);
+ reg = PARM_SET(p->width, p->shift, reg, rate_set->m);
+ writel(reg, pll->base + p->reg_off);
+
+ p = &pll->conf->od;
+ reg = readl(pll->base + p->reg_off);
+ reg = PARM_SET(p->width, p->shift, reg, rate_set->od);
+ writel(reg, pll->base + p->reg_off);
+
+ p = &pll->conf->n;
+ ret = meson_clk_pll_wait_lock(pll, p);
+ if (ret) {
+ pr_warn("%s: pll did not lock, trying to restore old rate %lu\n",
+ __func__, old_rate);
+ meson_clk_pll_set_rate(hw, old_rate, parent_rate);
+ }
+
+ return ret;
+}
+
+static const struct clk_ops meson_clk_pll_ops = {
+ .recalc_rate = meson_clk_pll_recalc_rate,
+ .round_rate = meson_clk_pll_round_rate,
+ .set_rate = meson_clk_pll_set_rate,
+};
+
+static const struct clk_ops meson_clk_pll_ro_ops = {
+ .recalc_rate = meson_clk_pll_recalc_rate,
+};
+
+struct clk *meson_clk_register_pll(const struct clk_conf *clk_conf,
+ void __iomem *reg_base,
+ spinlock_t *lock)
+{
+ struct clk *clk;
+ struct meson_clk_pll *clk_pll;
+ struct clk_init_data init;
+
+ clk_pll = kzalloc(sizeof(*clk_pll), GFP_KERNEL);
+ if (!clk_pll)
+ return ERR_PTR(-ENOMEM);
+
+ clk_pll->base = reg_base + clk_conf->reg_off;
+ clk_pll->lock = lock;
+ clk_pll->conf = clk_conf->conf.pll;
+
+ init.name = clk_conf->clk_name;
+ init.flags = clk_conf->flags | CLK_GET_RATE_NOCACHE;
+
+ init.parent_names = &clk_conf->clks_parent[0];
+ init.num_parents = 1;
+ init.ops = &meson_clk_pll_ro_ops;
+
+ /* If no rate_table is specified we assume the PLL is read-only */
+ if (clk_pll->conf->rate_table) {
+ int len;
+
+ for (len = 0; clk_pll->conf->rate_table[len].rate != 0; )
+ len++;
+
+ clk_pll->rate_count = len;
+ init.ops = &meson_clk_pll_ops;
+ }
+
+ clk_pll->hw.init = &init;
+
+ clk = clk_register(NULL, &clk_pll->hw);
+ if (IS_ERR(clk))
+ kfree(clk_pll);
+
+ return clk;
+}
Code Review / kvmfornfv.git / blobdiff