SPEAr: clk: Add VCO-PLL Synthesizer clock

All SPEAr SoC's contain PLLs. Their Fout is derived based on following equations

- In normal mode
  vco = (2 * M[15:8] * Fin)/N

- In Dithered mode
  vco = (2 * M[15:0] * Fin)/(256 * N)

pll_rate = vco/2^p

vco and pll are very closely bound to each other,
"vco needs to program: mode, m & n" and "pll needs to program p",
both share common enable/disable logic and registers.

This patch adds in support for this type of clock.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Reviewed-by: Mike Turquette <mturquette@linaro.org>

1 files changed, 363 insertions, 0 deletions

diff --git a/drivers/clk/spear/clk-vco-pll.c b/drivers/clk/spear/clk-vco-pll.c
new file mode 100644
index 000000000000..dcd4bdf4b0d9
--- /dev/null
+++ b/drivers/clk/spear/clk-vco-pll.c
@@ -0,0 +1,363 @@
+/*
+ * Copyright (C) 2012 ST Microelectronics
+ * Viresh Kumar <viresh.kumar@st.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * VCO-PLL clock implementation
+ */
+
+#define pr_fmt(fmt) "clk-vco-pll: " fmt
+
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include "clk.h"
+
+/*
+ * DOC: VCO-PLL clock
+ *
+ * VCO and PLL rate are derived from following equations:
+ *
+ * In normal mode
+ * vco = (2 * M[15:8] * Fin)/N
+ *
+ * In Dithered mode
+ * vco = (2 * M[15:0] * Fin)/(256 * N)
+ *
+ * pll_rate = pll/2^p
+ *
+ * vco and pll are very closely bound to each other, "vco needs to program:
+ * mode, m & n" and "pll needs to program p", both share common enable/disable
+ * logic.
+ *
+ * clk_register_vco_pll() registers instances of both vco & pll.
+ * CLK_SET_RATE_PARENT flag is forced for pll, as it will always pass its
+ * set_rate to vco. A single rate table exists for both the clocks, which
+ * configures m, n and p.
+ */
+
+/* PLL_CTR register masks */
+#define PLL_MODE_NORMAL         0
+#define PLL_MODE_FRACTION       1
+#define PLL_MODE_DITH_DSM       2
+#define PLL_MODE_DITH_SSM       3
+#define PLL_MODE_MASK           3
+#define PLL_MODE_SHIFT          3
+#define PLL_ENABLE              2
+
+#define PLL_LOCK_SHIFT          0
+#define PLL_LOCK_MASK           1
+
+/* PLL FRQ register masks */
+#define PLL_NORM_FDBK_M_MASK    0xFF
+#define PLL_NORM_FDBK_M_SHIFT   24
+#define PLL_DITH_FDBK_M_MASK    0xFFFF
+#define PLL_DITH_FDBK_M_SHIFT   16
+#define PLL_DIV_P_MASK          0x7
+#define PLL_DIV_P_SHIFT         8
+#define PLL_DIV_N_MASK          0xFF
+#define PLL_DIV_N_SHIFT         0
+
+#define to_clk_vco(_hw) container_of(_hw, struct clk_vco, hw)
+#define to_clk_pll(_hw) container_of(_hw, struct clk_pll, hw)
+
+/* Calculates pll clk rate for specific value of mode, m, n and p */
+static unsigned long pll_calc_rate(struct pll_rate_tbl *rtbl,
+                unsigned long prate, int index, unsigned long *pll_rate)
+{
+        unsigned long rate = prate;
+        unsigned int mode;
+
+        mode = rtbl[index].mode ? 256 : 1;
+        rate = (((2 * rate / 10000) * rtbl[index].m) / (mode * rtbl[index].n));
+
+        if (pll_rate)
+                *pll_rate = (rate / (1 << rtbl[index].p)) * 10000;
+
+        return rate * 10000;
+}
+
+static long clk_pll_round_rate_index(struct clk_hw *hw, unsigned long drate,
+                                unsigned long *prate, int *index)
+{
+        struct clk_pll *pll = to_clk_pll(hw);
+        unsigned long prev_rate, vco_prev_rate, rate = 0;
+        unsigned long vco_parent_rate =
+                __clk_get_rate(__clk_get_parent(__clk_get_parent(hw->clk)));
+
+        if (!prate) {
+                pr_err("%s: prate is must for pll clk\n", __func__);
+                return -EINVAL;
+        }
+
+        for (*index = 0; *index < pll->vco->rtbl_cnt; (*index)++) {
+                prev_rate = rate;
+                vco_prev_rate = *prate;
+                *prate = pll_calc_rate(pll->vco->rtbl, vco_parent_rate, *index,
+                                &rate);
+                if (drate < rate) {
+                        /* previous clock was best */
+                        if (*index) {
+                                rate = prev_rate;
+                                *prate = vco_prev_rate;
+                                (*index)--;
+                        }
+                        break;
+                }
+        }
+
+        return rate;
+}
+
+static long clk_pll_round_rate(struct clk_hw *hw, unsigned long drate,
+                                unsigned long *prate)
+{
+        int unused;
+
+        return clk_pll_round_rate_index(hw, drate, prate, &unused);
+}
+
+static unsigned long clk_pll_recalc_rate(struct clk_hw *hw, unsigned long
+                parent_rate)
+{
+        struct clk_pll *pll = to_clk_pll(hw);
+        unsigned long flags = 0;
+        unsigned int p;
+
+        if (pll->vco->lock)
+                spin_lock_irqsave(pll->vco->lock, flags);
+
+        p = readl_relaxed(pll->vco->cfg_reg);
+
+        if (pll->vco->lock)
+                spin_unlock_irqrestore(pll->vco->lock, flags);
+
+        p = (p >> PLL_DIV_P_SHIFT) & PLL_DIV_P_MASK;
+
+        return parent_rate / (1 << p);
+}
+
+static int clk_pll_set_rate(struct clk_hw *hw, unsigned long drate,
+                                unsigned long prate)
+{
+        struct clk_pll *pll = to_clk_pll(hw);
+        struct pll_rate_tbl *rtbl = pll->vco->rtbl;
+        unsigned long flags = 0, val;
+        int i;
+
+        clk_pll_round_rate_index(hw, drate, NULL, &i);
+
+        if (pll->vco->lock)
+                spin_lock_irqsave(pll->vco->lock, flags);
+
+        val = readl_relaxed(pll->vco->cfg_reg);
+        val &= ~(PLL_DIV_P_MASK << PLL_DIV_P_SHIFT);
+        val |= (rtbl[i].p & PLL_DIV_P_MASK) << PLL_DIV_P_SHIFT;
+        writel_relaxed(val, pll->vco->cfg_reg);
+
+        if (pll->vco->lock)
+                spin_unlock_irqrestore(pll->vco->lock, flags);
+
+        return 0;
+}
+
+static struct clk_ops clk_pll_ops = {
+        .recalc_rate = clk_pll_recalc_rate,
+        .round_rate = clk_pll_round_rate,
+        .set_rate = clk_pll_set_rate,
+};
+
+static inline unsigned long vco_calc_rate(struct clk_hw *hw,
+                unsigned long prate, int index)
+{
+        struct clk_vco *vco = to_clk_vco(hw);
+
+        return pll_calc_rate(vco->rtbl, prate, index, NULL);
+}
+
+static long clk_vco_round_rate(struct clk_hw *hw, unsigned long drate,
+                unsigned long *prate)
+{
+        struct clk_vco *vco = to_clk_vco(hw);
+        int unused;
+
+        return clk_round_rate_index(hw, drate, *prate, vco_calc_rate,
+                        vco->rtbl_cnt, &unused);
+}
+
+static unsigned long clk_vco_recalc_rate(struct clk_hw *hw,
+                unsigned long parent_rate)
+{
+        struct clk_vco *vco = to_clk_vco(hw);
+        unsigned long flags = 0;
+        unsigned int num = 2, den = 0, val, mode = 0;
+
+        if (vco->lock)
+                spin_lock_irqsave(vco->lock, flags);
+
+        mode = (readl_relaxed(vco->mode_reg) >> PLL_MODE_SHIFT) & PLL_MODE_MASK;
+
+        val = readl_relaxed(vco->cfg_reg);
+
+        if (vco->lock)
+                spin_unlock_irqrestore(vco->lock, flags);
+
+        den = (val >> PLL_DIV_N_SHIFT) & PLL_DIV_N_MASK;
+
+        /* calculate numerator & denominator */
+        if (!mode) {
+                /* Normal mode */
+                num *= (val >> PLL_NORM_FDBK_M_SHIFT) & PLL_NORM_FDBK_M_MASK;
+        } else {
+                /* Dithered mode */
+                num *= (val >> PLL_DITH_FDBK_M_SHIFT) & PLL_DITH_FDBK_M_MASK;
+                den *= 256;
+        }
+
+        if (!den) {
+                WARN(1, "%s: denominator can't be zero\n", __func__);
+                return 0;
+        }
+
+        return (((parent_rate / 10000) * num) / den) * 10000;
+}
+
+/* Configures new clock rate of vco */
+static int clk_vco_set_rate(struct clk_hw *hw, unsigned long drate,
+                                unsigned long prate)
+{
+        struct clk_vco *vco = to_clk_vco(hw);
+        struct pll_rate_tbl *rtbl = vco->rtbl;
+        unsigned long flags = 0, val;
+        int i;
+
+        clk_round_rate_index(hw, drate, prate, vco_calc_rate, vco->rtbl_cnt,
+                        &i);
+
+        if (vco->lock)
+                spin_lock_irqsave(vco->lock, flags);
+
+        val = readl_relaxed(vco->mode_reg);
+        val &= ~(PLL_MODE_MASK << PLL_MODE_SHIFT);
+        val |= (rtbl[i].mode & PLL_MODE_MASK) << PLL_MODE_SHIFT;
+        writel_relaxed(val, vco->mode_reg);
+
+        val = readl_relaxed(vco->cfg_reg);
+        val &= ~(PLL_DIV_N_MASK << PLL_DIV_N_SHIFT);
+        val |= (rtbl[i].n & PLL_DIV_N_MASK) << PLL_DIV_N_SHIFT;
+
+        val &= ~(PLL_DITH_FDBK_M_MASK << PLL_DITH_FDBK_M_SHIFT);
+        if (rtbl[i].mode)
+                val |= (rtbl[i].m & PLL_DITH_FDBK_M_MASK) <<
+                        PLL_DITH_FDBK_M_SHIFT;
+        else
+                val |= (rtbl[i].m & PLL_NORM_FDBK_M_MASK) <<
+                        PLL_NORM_FDBK_M_SHIFT;
+
+        writel_relaxed(val, vco->cfg_reg);
+
+        if (vco->lock)
+                spin_unlock_irqrestore(vco->lock, flags);
+
+        return 0;
+}
+
+static struct clk_ops clk_vco_ops = {
+        .recalc_rate = clk_vco_recalc_rate,
+        .round_rate = clk_vco_round_rate,
+        .set_rate = clk_vco_set_rate,
+};
+
+struct clk *clk_register_vco_pll(const char *vco_name, const char *pll_name,
+                const char *vco_gate_name, const char *parent_name,
+                unsigned long flags, void __iomem *mode_reg, void __iomem
+                *cfg_reg, struct pll_rate_tbl *rtbl, u8 rtbl_cnt,
+                spinlock_t *lock, struct clk **pll_clk,
+                struct clk **vco_gate_clk)
+{
+        struct clk_vco *vco;
+        struct clk_pll *pll;
+        struct clk *vco_clk, *tpll_clk, *tvco_gate_clk;
+        struct clk_init_data vco_init, pll_init;
+        const char **vco_parent_name;
+
+        if (!vco_name || !pll_name || !parent_name || !mode_reg || !cfg_reg ||
+                        !rtbl || !rtbl_cnt) {
+                pr_err("Invalid arguments passed");
+                return ERR_PTR(-EINVAL);
+        }
+
+        vco = kzalloc(sizeof(*vco), GFP_KERNEL);
+        if (!vco) {
+                pr_err("could not allocate vco clk\n");
+                return ERR_PTR(-ENOMEM);
+        }
+
+        pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+        if (!pll) {
+                pr_err("could not allocate pll clk\n");
+                goto free_vco;
+        }
+
+        /* struct clk_vco assignments */
+        vco->mode_reg = mode_reg;
+        vco->cfg_reg = cfg_reg;
+        vco->rtbl = rtbl;
+        vco->rtbl_cnt = rtbl_cnt;
+        vco->lock = lock;
+        vco->hw.init = &vco_init;
+
+        pll->vco = vco;
+        pll->hw.init = &pll_init;
+
+        if (vco_gate_name) {
+                tvco_gate_clk = clk_register_gate(NULL, vco_gate_name,
+                                parent_name, 0, mode_reg, PLL_ENABLE, 0, lock);
+                if (IS_ERR_OR_NULL(tvco_gate_clk))
+                        goto free_pll;
+
+                if (vco_gate_clk)
+                        *vco_gate_clk = tvco_gate_clk;
+                vco_parent_name = &vco_gate_name;
+        } else {
+                vco_parent_name = &parent_name;
+        }
+
+        vco_init.name = vco_name;
+        vco_init.ops = &clk_vco_ops;
+        vco_init.flags = flags;
+        vco_init.parent_names = vco_parent_name;
+        vco_init.num_parents = 1;
+
+        pll_init.name = pll_name;
+        pll_init.ops = &clk_pll_ops;
+        pll_init.flags = CLK_SET_RATE_PARENT;
+        pll_init.parent_names = &vco_name;
+        pll_init.num_parents = 1;
+
+        vco_clk = clk_register(NULL, &vco->hw);
+        if (IS_ERR_OR_NULL(vco_clk))
+                goto free_pll;
+
+        tpll_clk = clk_register(NULL, &pll->hw);
+        if (IS_ERR_OR_NULL(tpll_clk))
+                goto free_pll;
+
+        if (pll_clk)
+                *pll_clk = tpll_clk;
+
+        return vco_clk;
+
+free_pll:
+        kfree(pll);
+free_vco:
+        kfree(vco);
+
+        pr_err("Failed to register vco pll clock\n");
+
+        return ERR_PTR(-ENOMEM);
+}