clk-div6.c
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/*
* r8a7790 Common Clock Framework support
*
* Copyright (C) 2013 Renesas Solutions Corp.
*
* Contact: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*/
#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/of.h>
#include <linux/of_address.h>
#define CPG_DIV6_CKSTP BIT(8)
#define CPG_DIV6_DIV(d) ((d) & 0x3f)
#define CPG_DIV6_DIV_MASK 0x3f
/**
* struct div6_clock - MSTP gating clock
* @hw: handle between common and hardware-specific interfaces
* @reg: IO-remapped register
* @div: divisor value (1-64)
*/
struct div6_clock {
struct clk_hw hw;
void __iomem *reg;
unsigned int div;
};
#define to_div6_clock(_hw) container_of(_hw, struct div6_clock, hw)
static int cpg_div6_clock_enable(struct clk_hw *hw)
{
struct div6_clock *clock = to_div6_clock(hw);
clk_writel(CPG_DIV6_DIV(clock->div - 1), clock->reg);
return 0;
}
static void cpg_div6_clock_disable(struct clk_hw *hw)
{
struct div6_clock *clock = to_div6_clock(hw);
/* DIV6 clocks require the divisor field to be non-zero when stopping
* the clock.
*/
clk_writel(CPG_DIV6_CKSTP | CPG_DIV6_DIV(CPG_DIV6_DIV_MASK),
clock->reg);
}
static int cpg_div6_clock_is_enabled(struct clk_hw *hw)
{
struct div6_clock *clock = to_div6_clock(hw);
return !(clk_readl(clock->reg) & CPG_DIV6_CKSTP);
}
static unsigned long cpg_div6_clock_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
struct div6_clock *clock = to_div6_clock(hw);
unsigned int div = (clk_readl(clock->reg) & CPG_DIV6_DIV_MASK) + 1;
return parent_rate / div;
}
static unsigned int cpg_div6_clock_calc_div(unsigned long rate,
unsigned long parent_rate)
{
unsigned int div;
div = DIV_ROUND_CLOSEST(parent_rate, rate);
return clamp_t(unsigned int, div, 1, 64);
}
static long cpg_div6_clock_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
unsigned int div = cpg_div6_clock_calc_div(rate, *parent_rate);
return *parent_rate / div;
}
static int cpg_div6_clock_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct div6_clock *clock = to_div6_clock(hw);
unsigned int div = cpg_div6_clock_calc_div(rate, parent_rate);
clock->div = div;
/* Only program the new divisor if the clock isn't stopped. */
if (!(clk_readl(clock->reg) & CPG_DIV6_CKSTP))
clk_writel(CPG_DIV6_DIV(clock->div - 1), clock->reg);
return 0;
}
static const struct clk_ops cpg_div6_clock_ops = {
.enable = cpg_div6_clock_enable,
.disable = cpg_div6_clock_disable,
.is_enabled = cpg_div6_clock_is_enabled,
.recalc_rate = cpg_div6_clock_recalc_rate,
.round_rate = cpg_div6_clock_round_rate,
.set_rate = cpg_div6_clock_set_rate,
};
static void __init cpg_div6_clock_init(struct device_node *np)
{
struct clk_init_data init;
struct div6_clock *clock;
const char *parent_name;
const char *name;
struct clk *clk;
int ret;
clock = kzalloc(sizeof(*clock), GFP_KERNEL);
if (!clock) {
pr_err("%s: failed to allocate %s DIV6 clock\n",
__func__, np->name);
return;
}
/* Remap the clock register and read the divisor. Disabling the
* clock overwrites the divisor, so we need to cache its value for the
* enable operation.
*/
clock->reg = of_iomap(np, 0);
if (clock->reg == NULL) {
pr_err("%s: failed to map %s DIV6 clock register\n",
__func__, np->name);
goto error;
}
clock->div = (clk_readl(clock->reg) & CPG_DIV6_DIV_MASK) + 1;
/* Parse the DT properties. */
ret = of_property_read_string(np, "clock-output-names", &name);
if (ret < 0) {
pr_err("%s: failed to get %s DIV6 clock output name\n",
__func__, np->name);
goto error;
}
parent_name = of_clk_get_parent_name(np, 0);
if (parent_name == NULL) {
pr_err("%s: failed to get %s DIV6 clock parent name\n",
__func__, np->name);
goto error;
}
/* Register the clock. */
init.name = name;
init.ops = &cpg_div6_clock_ops;
init.flags = CLK_IS_BASIC;
init.parent_names = &parent_name;
init.num_parents = 1;
clock->hw.init = &init;
clk = clk_register(NULL, &clock->hw);
if (IS_ERR(clk)) {
pr_err("%s: failed to register %s DIV6 clock (%ld)\n",
__func__, np->name, PTR_ERR(clk));
goto error;
}
of_clk_add_provider(np, of_clk_src_simple_get, clk);
return;
error:
if (clock->reg)
iounmap(clock->reg);
kfree(clock);
}
CLK_OF_DECLARE(cpg_div6_clk, "renesas,cpg-div6-clock", cpg_div6_clock_init);