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SPEAr: clk: Add General Purpose Timer Synthesizer clock
All SPEAr SoC's contain GPT Synthesizers. Their Fout is derived from following equations: Fout= Fin/((2 ^ (N+1)) * (M+1)) 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>
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Viresh Kumar
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Arnd Bergmann
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May 12, 2012
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/* | ||
* 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 | ||
*/ | ||
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#define pr_fmt(fmt) "clk-gpt-synth: " fmt | ||
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#include <linux/clk-provider.h> | ||
#include <linux/slab.h> | ||
#include <linux/io.h> | ||
#include <linux/err.h> | ||
#include "clk.h" | ||
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#define GPT_MSCALE_MASK 0xFFF | ||
#define GPT_NSCALE_SHIFT 12 | ||
#define GPT_NSCALE_MASK 0xF | ||
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/* | ||
* 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)) | ||
*/ | ||
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#define to_clk_gpt(_hw) container_of(_hw, struct clk_gpt, hw) | ||
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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; | ||
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prate /= ((1 << (rtbl[index].nscale + 1)) * (rtbl[index].mscale + 1)); | ||
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return prate; | ||
} | ||
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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; | ||
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return clk_round_rate_index(hw, drate, *prate, gpt_calc_rate, | ||
gpt->rtbl_cnt, &unused); | ||
} | ||
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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; | ||
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if (gpt->lock) | ||
spin_lock_irqsave(gpt->lock, flags); | ||
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val = readl_relaxed(gpt->reg); | ||
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if (gpt->lock) | ||
spin_unlock_irqrestore(gpt->lock, flags); | ||
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div += val & GPT_MSCALE_MASK; | ||
div *= 1 << (((val >> GPT_NSCALE_SHIFT) & GPT_NSCALE_MASK) + 1); | ||
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if (!div) | ||
return 0; | ||
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return parent_rate / div; | ||
} | ||
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/* 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; | ||
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clk_round_rate_index(hw, drate, prate, gpt_calc_rate, gpt->rtbl_cnt, | ||
&i); | ||
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if (gpt->lock) | ||
spin_lock_irqsave(gpt->lock, flags); | ||
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val = readl(gpt->reg) & ~GPT_MSCALE_MASK; | ||
val &= ~(GPT_NSCALE_MASK << GPT_NSCALE_SHIFT); | ||
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val |= rtbl[i].mscale & GPT_MSCALE_MASK; | ||
val |= (rtbl[i].nscale & GPT_NSCALE_MASK) << GPT_NSCALE_SHIFT; | ||
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writel_relaxed(val, gpt->reg); | ||
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if (gpt->lock) | ||
spin_unlock_irqrestore(gpt->lock, flags); | ||
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return 0; | ||
} | ||
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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, | ||
}; | ||
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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; | ||
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if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) { | ||
pr_err("Invalid arguments passed"); | ||
return ERR_PTR(-EINVAL); | ||
} | ||
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gpt = kzalloc(sizeof(*gpt), GFP_KERNEL); | ||
if (!gpt) { | ||
pr_err("could not allocate gpt clk\n"); | ||
return ERR_PTR(-ENOMEM); | ||
} | ||
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/* struct clk_gpt assignments */ | ||
gpt->reg = reg; | ||
gpt->rtbl = rtbl; | ||
gpt->rtbl_cnt = rtbl_cnt; | ||
gpt->lock = lock; | ||
gpt->hw.init = &init; | ||
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init.name = name; | ||
init.ops = &clk_gpt_ops; | ||
init.flags = flags; | ||
init.parent_names = &parent_name; | ||
init.num_parents = 1; | ||
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clk = clk_register(NULL, &gpt->hw); | ||
if (!IS_ERR_OR_NULL(clk)) | ||
return clk; | ||
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pr_err("clk register failed\n"); | ||
kfree(gpt); | ||
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return NULL; | ||
} |
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