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path: root/drivers/clk/mxs/clk-frac.c
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-rw-r--r--drivers/clk/mxs/clk-frac.c138
1 files changed, 138 insertions, 0 deletions
diff --git a/drivers/clk/mxs/clk-frac.c b/drivers/clk/mxs/clk-frac.c
new file mode 100644
index 0000000000..bba0d840dd
--- /dev/null
+++ b/drivers/clk/mxs/clk-frac.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2012 Freescale Semiconductor, Inc.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include "clk.h"
+
+/**
+ * struct clk_frac - mxs fractional divider clock
+ * @hw: clk_hw for the fractional divider clock
+ * @reg: register address
+ * @shift: the divider bit shift
+ * @width: the divider bit width
+ * @busy: busy bit shift
+ *
+ * The clock is an adjustable fractional divider with a busy bit to wait
+ * when the divider is adjusted.
+ */
+struct clk_frac {
+ struct clk_hw hw;
+ void __iomem *reg;
+ u8 shift;
+ u8 width;
+ u8 busy;
+};
+
+#define to_clk_frac(_hw) container_of(_hw, struct clk_frac, hw)
+
+static unsigned long clk_frac_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct clk_frac *frac = to_clk_frac(hw);
+ u32 div;
+ u64 tmp_rate;
+
+ div = readl_relaxed(frac->reg) >> frac->shift;
+ div &= (1 << frac->width) - 1;
+
+ tmp_rate = (u64)parent_rate * div;
+ return tmp_rate >> frac->width;
+}
+
+static long clk_frac_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ struct clk_frac *frac = to_clk_frac(hw);
+ unsigned long parent_rate = *prate;
+ u32 div;
+ u64 tmp, tmp_rate, result;
+
+ if (rate > parent_rate)
+ return -EINVAL;
+
+ tmp = rate;
+ tmp <<= frac->width;
+ do_div(tmp, parent_rate);
+ div = tmp;
+
+ if (!div)
+ return -EINVAL;
+
+ tmp_rate = (u64)parent_rate * div;
+ result = tmp_rate >> frac->width;
+ if ((result << frac->width) < tmp_rate)
+ result += 1;
+ return result;
+}
+
+static int clk_frac_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct clk_frac *frac = to_clk_frac(hw);
+ unsigned long flags;
+ u32 div, val;
+ u64 tmp;
+
+ if (rate > parent_rate)
+ return -EINVAL;
+
+ tmp = rate;
+ tmp <<= frac->width;
+ do_div(tmp, parent_rate);
+ div = tmp;
+
+ if (!div)
+ return -EINVAL;
+
+ spin_lock_irqsave(&mxs_lock, flags);
+
+ val = readl_relaxed(frac->reg);
+ val &= ~(((1 << frac->width) - 1) << frac->shift);
+ val |= div << frac->shift;
+ writel_relaxed(val, frac->reg);
+
+ spin_unlock_irqrestore(&mxs_lock, flags);
+
+ return mxs_clk_wait(frac->reg, frac->busy);
+}
+
+static const struct clk_ops clk_frac_ops = {
+ .recalc_rate = clk_frac_recalc_rate,
+ .round_rate = clk_frac_round_rate,
+ .set_rate = clk_frac_set_rate,
+};
+
+struct clk *mxs_clk_frac(const char *name, const char *parent_name,
+ void __iomem *reg, u8 shift, u8 width, u8 busy)
+{
+ struct clk_frac *frac;
+ struct clk *clk;
+ struct clk_init_data init;
+
+ frac = kzalloc(sizeof(*frac), GFP_KERNEL);
+ if (!frac)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &clk_frac_ops;
+ init.flags = CLK_SET_RATE_PARENT;
+ init.parent_names = (parent_name ? &parent_name: NULL);
+ init.num_parents = (parent_name ? 1 : 0);
+
+ frac->reg = reg;
+ frac->shift = shift;
+ frac->width = width;
+ frac->busy = busy;
+ frac->hw.init = &init;
+
+ clk = clk_register(NULL, &frac->hw);
+ if (IS_ERR(clk))
+ kfree(frac);
+
+ return clk;
+}