[PATCH v12 2/5] clk: imx: add fractional PLL output clock

Abel Vesa
2018-11-07T12:38:50Z

From: Lucas Stach <l.stach@pengutronix.de>

This is a new fractional clock type introduced on i.MX8.

The description of this fractional clock can be found here:

https://www.nxp.com/docs/en/reference-manual/IMX8MDQLQRM.pdf#page=834

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
---
drivers/clk/imx/Makefile | 1 +
drivers/clk/imx/clk-frac-pll.c | 221 +++++++++++++++++++++++++++++++++++++++++
drivers/clk/imx/clk.h | 3 +
3 files changed, 225 insertions(+)
create mode 100644 drivers/clk/imx/clk-frac-pll.c

diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
index 8c3baa7..4893c1f 100644
--- a/drivers/clk/imx/Makefile
+++ b/drivers/clk/imx/Makefile
@@ -6,6 +6,7 @@ obj-y += \
clk-cpu.o \
clk-fixup-div.o \
clk-fixup-mux.o \
+ clk-frac-pll.o \
clk-gate-exclusive.o \
clk-gate2.o \
clk-pllv1.o \
diff --git a/drivers/clk/imx/clk-frac-pll.c b/drivers/clk/imx/clk-frac-pll.c
new file mode 100644
index 0000000..a800093
--- /dev/null
+++ b/drivers/clk/imx/clk-frac-pll.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2018 NXP.
+ *
+ * This driver supports the fractional plls found in the imx8m SOCs
+ *
+ * Documentation for this fractional pll can be found at:
+ * https://www.nxp.com/docs/en/reference-manual/IMX8MDQLQRM.pdf#page=834
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/iopoll.h>
+#include <linux/slab.h>
+#include <linux/bitfield.h>
+
+#define PLL_CFG0 0x0
+#define PLL_CFG1 0x4
+
+#define PLL_LOCK_STATUS BIT(31)
+#define PLL_PD_MASK BIT(19)
+#define PLL_BYPASS_MASK BIT(14)
+#define PLL_NEWDIV_VAL BIT(12)
+#define PLL_NEWDIV_ACK BIT(11)
+#define PLL_FRAC_DIV_MASK GENMASK(30, 7)
+#define PLL_INT_DIV_MASK GENMASK(6, 0)
+#define PLL_OUTPUT_DIV_MASK GENMASK(4, 0)
+#define PLL_FRAC_DENOM 0x1000000
+
+#define PLL_FRAC_LOCK_TIMEOUT 10000
+#define PLL_FRAC_ACK_TIMEOUT 500000
+
+struct clk_frac_pll {
+ struct clk_hw hw;
+ void __iomem *base;
+};
+
+#define to_clk_frac_pll(_hw) container_of(_hw, struct clk_frac_pll, hw)
+
+static int clk_wait_lock(struct clk_frac_pll *pll)
+{
+ u32 val;
+
+ return readl_poll_timeout(pll->base, val, val & PLL_LOCK_STATUS, 0,
+ PLL_FRAC_LOCK_TIMEOUT);
+}
+
+static int clk_wait_ack(struct clk_frac_pll *pll)
+{
+ u32 val;
+
+ /* return directly if the pll is in powerdown or in bypass */
+ if (readl_relaxed(pll->base) & (PLL_PD_MASK | PLL_BYPASS_MASK))
+ return 0;
+
+ /* Wait for the pll's divfi and divff to be reloaded */
+ return readl_poll_timeout(pll->base, val, val & PLL_NEWDIV_ACK, 0,
+ PLL_FRAC_ACK_TIMEOUT);
+}
+
+static int clk_pll_prepare(struct clk_hw *hw)
+{
+ struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+ u32 val;
+
+ val = readl_relaxed(pll->base + PLL_CFG0);
+ val &= ~PLL_PD_MASK;
+ writel_relaxed(val, pll->base + PLL_CFG0);
+
+ return clk_wait_lock(pll);
+}
+
+static void clk_pll_unprepare(struct clk_hw *hw)
+{
+ struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+ u32 val;
+
+ val = readl_relaxed(pll->base + PLL_CFG0);
+ val |= PLL_PD_MASK;
+ writel_relaxed(val, pll->base + PLL_CFG0);
+}
+
+static int clk_pll_is_prepared(struct clk_hw *hw)
+{
+ struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+ u32 val;
+
+ val = readl_relaxed(pll->base + PLL_CFG0);
+ return (val & PLL_PD_MASK) ? 0 : 1;
+}
+
+static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+ u32 val, divff, divfi, divq;
+ u64 temp64 = parent_rate;
+
+ val = readl_relaxed(pll->base + PLL_CFG0);
+ divq = ((val & PLL_OUTPUT_DIV_MASK) + 1) * 2;
+ val = readl_relaxed(pll->base + PLL_CFG1);
+ divff = FIELD_GET(PLL_FRAC_DIV_MASK, val);
+ divfi = val & PLL_INT_DIV_MASK;
+
+ temp64 *= 8;
+ temp64 *= divff;
+ do_div(temp64, PLL_FRAC_DENOM);
+ temp64 /= divq;
+
+ return parent_rate * 8 * (divfi + 1) / divq + (unsigned long)temp64;
+}
+
+static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ u64 parent_rate = *prate;
+ u32 divff, divfi;
+ u64 temp64;
+
+ parent_rate *= 8;
+ rate *= 2;
+ divfi = rate / parent_rate;
+ temp64 = rate - divfi * parent_rate;
+ temp64 *= PLL_FRAC_DENOM;
+ do_div(temp64, parent_rate);
+ divff = temp64;
+
+ temp64 = parent_rate;
+ temp64 *= divff;
+ do_div(temp64, PLL_FRAC_DENOM);
+
+ return (parent_rate * divfi + temp64) / 2;
+}
+
+/*
+ * To simplify the clock calculation, we can keep the 'PLL_OUTPUT_VAL' at zero
+ * (means the PLL output will be divided by 2). So the PLL output can use
+ * the below formula:
+ * pllout = parent_rate * 8 / 2 * DIVF_VAL;
+ * where DIVF_VAL = 1 + DIVFI + DIVFF / 2^24.
+ */
+static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct clk_frac_pll *pll = to_clk_frac_pll(hw);
+ u32 val, divfi, divff;
+ u64 temp64 = parent_rate;
+ int ret;
+
+ parent_rate *= 8;
+ rate *= 2;
+ divfi = rate / parent_rate;
+ temp64 *= rate - divfi;
+ temp64 *= PLL_FRAC_DENOM;
+ do_div(temp64, parent_rate);
+ divff = temp64;
+
+ val = readl_relaxed(pll->base + PLL_CFG1);
+ val &= ~(PLL_FRAC_DIV_MASK | PLL_INT_DIV_MASK);
+ val |= (divff << 7) | (divfi - 1);
+ writel_relaxed(val, pll->base + PLL_CFG1);
+
+ val = readl_relaxed(pll->base + PLL_CFG0);
+ val &= ~0x1f;
+ writel_relaxed(val, pll->base + PLL_CFG0);
+
+ /* Set the NEV_DIV_VAL to reload the DIVFI and DIVFF */
+ val = readl_relaxed(pll->base + PLL_CFG0);
+ val |= PLL_NEWDIV_VAL;
+ writel_relaxed(val, pll->base + PLL_CFG0);
+
+ ret = clk_wait_ack(pll);
+
+ /* clear the NEV_DIV_VAL */
+ val = readl_relaxed(pll->base + PLL_CFG0);
+ val &= ~PLL_NEWDIV_VAL;
+ writel_relaxed(val, pll->base + PLL_CFG0);
+
+ return ret;
+}
+
+static const struct clk_ops clk_frac_pll_ops = {
+ .prepare = clk_pll_prepare,
+ .unprepare = clk_pll_unprepare,
+ .is_prepared = clk_pll_is_prepared,
+ .recalc_rate = clk_pll_recalc_rate,
+ .round_rate = clk_pll_round_rate,
+ .set_rate = clk_pll_set_rate,
+};
+
+struct clk *imx_clk_frac_pll(const char *name, const char *parent_name,
+ void __iomem *base)
+{
+ struct clk_init_data init;
+ struct clk_frac_pll *pll;
+ struct clk_hw *hw;
+ int ret;
+
+ pll = kzalloc(sizeof(*pll), GFP_KERNEL);
+ if (!pll)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &clk_frac_pll_ops;
+ init.flags = 0;
+ init.parent_names = &parent_name;
+ init.num_parents = 1;
+
+ pll->base = base;
+ pll->hw.init = &init;
+
+ hw = &pll->hw;
+
+ ret = clk_hw_register(NULL, hw);
+ if (ret) {
+ kfree(pll);
+ return ERR_CAST(hw);
+ }
+
+ return hw->clk;
+}
diff --git a/drivers/clk/imx/clk.h b/drivers/clk/imx/clk.h
index 5895e223..44a1f14 100644
--- a/drivers/clk/imx/clk.h
+++ b/drivers/clk/imx/clk.h
@@ -27,6 +27,9 @@ struct clk *imx_clk_pllv1(enum imx_pllv1_type type, const char *name,
struct clk *imx_clk_pllv2(const char *name, const char *parent,
void __iomem *base);

+struct clk *imx_clk_frac_pll(const char *name, const char *parent_name,
+ void __iomem *base);
+
enum imx_pllv3_type {
IMX_PLLV3_GENERIC,
IMX_PLLV3_SYS,
--
2.7.4