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path: root/drivers/clk/spear/clk-gpt-synth.c
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-rw-r--r--drivers/clk/spear/clk-gpt-synth.c154
1 files changed, 154 insertions, 0 deletions
diff --git a/drivers/clk/spear/clk-gpt-synth.c b/drivers/clk/spear/clk-gpt-synth.c
new file mode 100644
index 00000000000..b471c9762a9
--- /dev/null
+++ b/drivers/clk/spear/clk-gpt-synth.c
@@ -0,0 +1,154 @@
+/*
+ * 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.
+ *
+ * General Purpose Timer Synthesizer clock implementation
+ */
+
+#define pr_fmt(fmt) "clk-gpt-synth: " fmt
+
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include "clk.h"
+
+#define GPT_MSCALE_MASK 0xFFF
+#define GPT_NSCALE_SHIFT 12
+#define GPT_NSCALE_MASK 0xF
+
+/*
+ * DOC: General Purpose Timer Synthesizer clock
+ *
+ * Calculates gpt synth clk rate for different values of mscale and nscale
+ *
+ * Fout= Fin/((2 ^ (N+1)) * (M+1))
+ */
+
+#define to_clk_gpt(_hw) container_of(_hw, struct clk_gpt, hw)
+
+static unsigned long gpt_calc_rate(struct clk_hw *hw, unsigned long prate,
+ int index)
+{
+ struct clk_gpt *gpt = to_clk_gpt(hw);
+ struct gpt_rate_tbl *rtbl = gpt->rtbl;
+
+ prate /= ((1 << (rtbl[index].nscale + 1)) * (rtbl[index].mscale + 1));
+
+ return prate;
+}
+
+static long clk_gpt_round_rate(struct clk_hw *hw, unsigned long drate,
+ unsigned long *prate)
+{
+ struct clk_gpt *gpt = to_clk_gpt(hw);
+ int unused;
+
+ return clk_round_rate_index(hw, drate, *prate, gpt_calc_rate,
+ gpt->rtbl_cnt, &unused);
+}
+
+static unsigned long clk_gpt_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct clk_gpt *gpt = to_clk_gpt(hw);
+ unsigned long flags = 0;
+ unsigned int div = 1, val;
+
+ if (gpt->lock)
+ spin_lock_irqsave(gpt->lock, flags);
+
+ val = readl_relaxed(gpt->reg);
+
+ if (gpt->lock)
+ spin_unlock_irqrestore(gpt->lock, flags);
+
+ div += val & GPT_MSCALE_MASK;
+ div *= 1 << (((val >> GPT_NSCALE_SHIFT) & GPT_NSCALE_MASK) + 1);
+
+ if (!div)
+ return 0;
+
+ return parent_rate / div;
+}
+
+/* Configures new clock rate of gpt */
+static int clk_gpt_set_rate(struct clk_hw *hw, unsigned long drate,
+ unsigned long prate)
+{
+ struct clk_gpt *gpt = to_clk_gpt(hw);
+ struct gpt_rate_tbl *rtbl = gpt->rtbl;
+ unsigned long flags = 0, val;
+ int i;
+
+ clk_round_rate_index(hw, drate, prate, gpt_calc_rate, gpt->rtbl_cnt,
+ &i);
+
+ if (gpt->lock)
+ spin_lock_irqsave(gpt->lock, flags);
+
+ val = readl(gpt->reg) & ~GPT_MSCALE_MASK;
+ val &= ~(GPT_NSCALE_MASK << GPT_NSCALE_SHIFT);
+
+ val |= rtbl[i].mscale & GPT_MSCALE_MASK;
+ val |= (rtbl[i].nscale & GPT_NSCALE_MASK) << GPT_NSCALE_SHIFT;
+
+ writel_relaxed(val, gpt->reg);
+
+ if (gpt->lock)
+ spin_unlock_irqrestore(gpt->lock, flags);
+
+ return 0;
+}
+
+static struct clk_ops clk_gpt_ops = {
+ .recalc_rate = clk_gpt_recalc_rate,
+ .round_rate = clk_gpt_round_rate,
+ .set_rate = clk_gpt_set_rate,
+};
+
+struct clk *clk_register_gpt(const char *name, const char *parent_name, unsigned
+ long flags, void __iomem *reg, struct gpt_rate_tbl *rtbl, u8
+ rtbl_cnt, spinlock_t *lock)
+{
+ struct clk_init_data init;
+ struct clk_gpt *gpt;
+ struct clk *clk;
+
+ if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) {
+ pr_err("Invalid arguments passed");
+ return ERR_PTR(-EINVAL);
+ }
+
+ gpt = kzalloc(sizeof(*gpt), GFP_KERNEL);
+ if (!gpt) {
+ pr_err("could not allocate gpt clk\n");
+ return ERR_PTR(-ENOMEM);
+ }
+
+ /* struct clk_gpt assignments */
+ gpt->reg = reg;
+ gpt->rtbl = rtbl;
+ gpt->rtbl_cnt = rtbl_cnt;
+ gpt->lock = lock;
+ gpt->hw.init = &init;
+
+ init.name = name;
+ init.ops = &clk_gpt_ops;
+ init.flags = flags;
+ init.parent_names = &parent_name;
+ init.num_parents = 1;
+
+ clk = clk_register(NULL, &gpt->hw);
+ if (!IS_ERR_OR_NULL(clk))
+ return clk;
+
+ pr_err("clk register failed\n");
+ kfree(gpt);
+
+ return NULL;
+}