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clk: add lpc18xx creg clk driver 

The CREG block on lpc18xx contains configuration register
for two low power clocks. Support enabling of these two
clocks with a clk driver that access CREG trough the
syscon regmap interface.

These clocks are needed to support peripherals like the
internal RTC on lpc18xx.

Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
This commit is contained in:
Joachim Eastwood 2016-03-03 22:47:04 +01:00 committed by Stephen Boyd
parent 37655fae0c
commit 378523d150
2 changed files with 227 additions and 0 deletions
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1
drivers/clk/nxp/Makefile
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@ -1,3 +1,4 @@
obj-$(CONFIG_ARCH_LPC18XX) += clk-lpc18xx-cgu.o
obj-$(CONFIG_ARCH_LPC18XX) += clk-lpc18xx-ccu.o
obj-$(CONFIG_ARCH_LPC18XX) += clk-lpc18xx-creg.o
obj-$(CONFIG_ARCH_LPC32XX) += clk-lpc32xx.o

226
drivers/clk/nxp/clk-lpc18xx-creg.c Normal file
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@ -0,0 +1,226 @@
/*
* Clk driver for NXP LPC18xx/43xx Configuration Registers (CREG)
*
* Copyright (C) 2015 Joachim Eastwood <manabian@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.
*/
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#define LPC18XX_CREG_CREG0 0x004
#define LPC18XX_CREG_CREG0_EN1KHZ BIT(0)
#define LPC18XX_CREG_CREG0_EN32KHZ BIT(1)
#define LPC18XX_CREG_CREG0_RESET32KHZ BIT(2)
#define LPC18XX_CREG_CREG0_PD32KHZ BIT(3)
#define to_clk_creg(_hw) container_of(_hw, struct clk_creg_data, hw)
enum {
CREG_CLK_1KHZ,
CREG_CLK_32KHZ,
CREG_CLK_MAX,
};
struct clk_creg_data {
struct clk_hw hw;
const char *name;
struct regmap *reg;
unsigned int en_mask;
const struct clk_ops *ops;
};
#define CREG_CLK(_name, _emask, _ops) \
{ \
.name = _name, \
.en_mask = LPC18XX_CREG_CREG0_##_emask, \
.ops = &_ops, \
}
static int clk_creg_32k_prepare(struct clk_hw *hw)
{
struct clk_creg_data *creg = to_clk_creg(hw);
int ret;
ret = regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0,
LPC18XX_CREG_CREG0_PD32KHZ |
LPC18XX_CREG_CREG0_RESET32KHZ, 0);
/*
* Powering up the 32k oscillator takes a long while
* and sadly there aren't any status bit to poll.
*/
msleep(2500);
return ret;
}
static void clk_creg_32k_unprepare(struct clk_hw *hw)
{
struct clk_creg_data *creg = to_clk_creg(hw);
regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0,
LPC18XX_CREG_CREG0_PD32KHZ,
LPC18XX_CREG_CREG0_PD32KHZ);
}
static int clk_creg_32k_is_prepared(struct clk_hw *hw)
{
struct clk_creg_data *creg = to_clk_creg(hw);
u32 reg;
regmap_read(creg->reg, LPC18XX_CREG_CREG0, &reg);
return !(reg & LPC18XX_CREG_CREG0_PD32KHZ) &&
!(reg & LPC18XX_CREG_CREG0_RESET32KHZ);
}
static unsigned long clk_creg_1k_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
return parent_rate / 32;
}
static int clk_creg_enable(struct clk_hw *hw)
{
struct clk_creg_data *creg = to_clk_creg(hw);
return regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0,
creg->en_mask, creg->en_mask);
}
static void clk_creg_disable(struct clk_hw *hw)
{
struct clk_creg_data *creg = to_clk_creg(hw);
regmap_update_bits(creg->reg, LPC18XX_CREG_CREG0,
creg->en_mask, 0);
}
static int clk_creg_is_enabled(struct clk_hw *hw)
{
struct clk_creg_data *creg = to_clk_creg(hw);
u32 reg;
regmap_read(creg->reg, LPC18XX_CREG_CREG0, &reg);
return !!(reg & creg->en_mask);
}
static const struct clk_ops clk_creg_32k = {
.enable = clk_creg_enable,
.disable = clk_creg_disable,
.is_enabled = clk_creg_is_enabled,
.prepare = clk_creg_32k_prepare,
.unprepare = clk_creg_32k_unprepare,
.is_prepared = clk_creg_32k_is_prepared,
};
static const struct clk_ops clk_creg_1k = {
.enable = clk_creg_enable,
.disable = clk_creg_disable,
.is_enabled = clk_creg_is_enabled,
.recalc_rate = clk_creg_1k_recalc_rate,
};
static struct clk_creg_data clk_creg_clocks[] = {
[CREG_CLK_1KHZ] = CREG_CLK("1khz_clk", EN1KHZ, clk_creg_1k),
[CREG_CLK_32KHZ] = CREG_CLK("32khz_clk", EN32KHZ, clk_creg_32k),
};
static struct clk *clk_register_creg_clk(struct device *dev,
struct clk_creg_data *creg_clk,
const char **parent_name,
struct regmap *syscon)
{
struct clk_init_data init;
init.ops = creg_clk->ops;
init.name = creg_clk->name;
init.parent_names = parent_name;
init.num_parents = 1;
creg_clk->reg = syscon;
creg_clk->hw.init = &init;
if (dev)
return devm_clk_register(dev, &creg_clk->hw);
return clk_register(NULL, &creg_clk->hw);
}
static struct clk *clk_creg_early[CREG_CLK_MAX];
static struct clk_onecell_data clk_creg_early_data = {
.clks = clk_creg_early,
.clk_num = CREG_CLK_MAX,
};
static void __init lpc18xx_creg_clk_init(struct device_node *np)
{
const char *clk_32khz_parent;
struct regmap *syscon;
syscon = syscon_node_to_regmap(np->parent);
if (IS_ERR(syscon)) {
pr_err("%s: syscon lookup failed\n", __func__);
return;
}
clk_32khz_parent = of_clk_get_parent_name(np, 0);
clk_creg_early[CREG_CLK_32KHZ] =
clk_register_creg_clk(NULL, &clk_creg_clocks[CREG_CLK_32KHZ],
&clk_32khz_parent, syscon);
clk_creg_early[CREG_CLK_1KHZ] = ERR_PTR(-EPROBE_DEFER);
of_clk_add_provider(np, of_clk_src_onecell_get, &clk_creg_early_data);
}
CLK_OF_DECLARE(lpc18xx_creg_clk, "nxp,lpc1850-creg-clk", lpc18xx_creg_clk_init);
static struct clk *clk_creg[CREG_CLK_MAX];
static struct clk_onecell_data clk_creg_data = {
.clks = clk_creg,
.clk_num = CREG_CLK_MAX,
};
static int lpc18xx_creg_clk_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct regmap *syscon;
syscon = syscon_node_to_regmap(np->parent);
if (IS_ERR(syscon)) {
dev_err(&pdev->dev, "syscon lookup failed\n");
return PTR_ERR(syscon);
}
clk_creg[CREG_CLK_32KHZ] = clk_creg_early[CREG_CLK_32KHZ];
clk_creg[CREG_CLK_1KHZ] =
clk_register_creg_clk(NULL, &clk_creg_clocks[CREG_CLK_1KHZ],
&clk_creg_clocks[CREG_CLK_32KHZ].name,
syscon);
return of_clk_add_provider(np, of_clk_src_onecell_get, &clk_creg_data);
}
static const struct of_device_id lpc18xx_creg_clk_of_match[] = {
{ .compatible = "nxp,lpc1850-creg-clk" },
{},
};
static struct platform_driver lpc18xx_creg_clk_driver = {
.probe = lpc18xx_creg_clk_probe,
.driver = {
.name = "lpc18xx-creg-clk",
.of_match_table = lpc18xx_creg_clk_of_match,
},
};
builtin_platform_driver(lpc18xx_creg_clk_driver);