original development tree for Linux kernel GTP module; now long in mainline.
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linux-gtp/drivers/clk/spear/clk-gpt-synth.c

154 lines
3.5 KiB

/*
* Copyright (C) 2012 ST Microelectronics
* Viresh Kumar <viresh.linux@gmail.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;
}