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Date: Tue, 29 Jul 2014 17:35:39 +0800
From: caesar <caesar.wang@...k-chips.com>
To: Olof Johansson <olof@...om.net>
CC: Doug Anderson <dianders@...omium.org>,
Thierry Reding <thierry.reding@...il.com>,
linux-pwm@...r.kernel.org,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] pwm: add this patch to support the new pwm of
Rockchip SoCs
Hi Olof,
Sorry, I didn't understand all of what you mean.
Please allow me to paste the following code [1].
在 2014年07月29日 00:58, Olof Johansson 写道:
> On Mon, Jul 28, 2014 at 4:19 AM, caesar <caesar.wang@...k-chips.com> wrote:
>> Doug,
>> 在 2014年07月28日 12:01, Doug Anderson 写道:
>>
>>> Caesar,
>>>
>>> On Sun, Jul 27, 2014 at 7:00 AM, caesar <caesar.wang@...k-chips.com>
>>> wrote:
>>>> /*I think will be show the faill log:->
>>>>
>>>> * rockchip-pwm ff9301a0.pwm: can't request region for resource [mem
>>>> 0xff9301a0-0xff93019f]
>>>> */
>>>>
>>>> pc->base = devm_ioremap_resource(dev, regs);
>>> Did you actually code this up and try it and get this error?
>> Yeah.
>>
>>> I hadn't
>>> tried it but I researched other dts files and it looked as if there
>>> was one example that was doing this. ...but perhaps it wasn't
>>> actually doing the ioremap_resource on both ranges.
>>>
>>> I'd imagine that this is _probably_ equivalent to what Thierry was
>>> suggesting, so if it didn't work then maybe Thierry's won't work
>>> either?
>>>
>>> I don't have any other great suggestions other than doing two memory
>>> ranges for lcdc:
>>>
>>> lcdc@...30000 {
>>> compatible = "rockchip,rk3288-lcdc";
>>> reg = <0xff930000 0x1a0>, <0xff9301b0 0xfe50>;
>>> ...
>>> };
>>> pwm@...301a0 {
>>> compatible = "rockchip,vop-pwm";
>>> reg = <0xff9301a0 0x10>;
>>> ...
>>> };
>>>
>>> ...but I am certainly nowhere near an expert on this stuff...
>>>
>>> -Doug
>>>
>>>
>>>
>> I has solve in lcdc driver,but I always feel awkward. I think a good way to
>> solve in pwm driver.
>> Unfortunately that so far ,I have not a good idle in pwm driver.
>>
>> Maybe,I let do it that way in lcdc driver.
> I think there's an easier way to do this, by not focusing _too_ much
> on the device tree:
>
> * Define a platform_data structure for the PWM driver, which contains
> readl/writel accessors as well as the device type (i.e. what you use
> the compatible field and the lookup table for today).
Maybe, as the following code: "pwm_data_vop" has been implement it. right?
> * Populate the platform_device in the clcd driver, and register that
Yeah,the lcdc driver can register it.
> * Make the PWM driver probe as a regular platform device if pdata is passed
> * Make a readl/writel wrapper that either falls back to native
> readl/writel when there aren't any passed in, or make the DT code fill
> in the pdata with the native versions in that case.
Sorry,This step I don't understand it. Perhaps, could you give a simple
case for it ?:-P
> Going full MFD on this seems overkill, unless there is also a shared
> interrupt that needs to be handled.
>
> -Olof
>
>
>
>
[1]:The driver/pwm/pwm-rockchip.c
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/time.h>
#define PWM_CNTR 0x00 /* Counter register */
#define PWM_HRC 0x04 /* High reference register */
#define PWM_LRC 0x08 /* Low reference register */
#define PWM_CTRL 0x0c /* Control register */
#define PWM_CTRL_TIMER_EN (1 << 0)
#define PWM_CTRL_OUTPUT_EN (1 << 3)
#define PRESCALER 2
#define PWM_ENABLE (1 << 0)
#define PWM_CONTINUOUS (1 << 1)
#define PWM_DUTY_POSITIVE (1 << 3)
#define PWM_INACTIVE_NEGATIVE (0 << 4)
#define PWM_OUTPUT_LEFT (0 << 5)
#define PWM_LP_DISABLE (0 << 8)
struct rockchip_pwm_chip {
struct pwm_chip chip;
struct clk *clk;
const struct rockchip_pwm_data *data;
void __iomem *base;
};
struct rockchip_pwm_regs {
unsigned long duty;
unsigned long period;
unsigned long cntr;
unsigned long ctrl;
};
struct rockchip_pwm_data {
struct rockchip_pwm_regs regs;
unsigned int prescaler;
void (*set_enable)(struct pwm_chip *chip, bool enable);
};
static inline struct rockchip_pwm_chip *to_rockchip_pwm_chip(struct
pwm_chip *c)
{
return container_of(c, struct rockchip_pwm_chip, chip);
}
static void rockchip_pwm_set_enable_v1(struct pwm_chip *chip, bool enable)
{
struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
u32 val = 0;
u32 enable_conf = PWM_CTRL_OUTPUT_EN | PWM_CTRL_TIMER_EN;
val = readl_relaxed(pc->base + pc->data->regs.ctrl);
if (enable)
val |= enable_conf;
else
val &= ~enable_conf;
writel_relaxed(val, pc->base + pc->data->regs.ctrl);
}
static void rockchip_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
{
struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
u32 val = 0;
u32 enable_conf = PWM_OUTPUT_LEFT | PWM_LP_DISABLE | PWM_ENABLE |
PWM_CONTINUOUS | PWM_DUTY_POSITIVE | PWM_INACTIVE_NEGATIVE;
val = readl_relaxed(pc->base + pc->data->regs.ctrl);
if (enable)
val |= enable_conf;
else
val &= ~enable_conf;
writel_relaxed(val, pc->base + pc->data->regs.ctrl);
}
static int rockchip_pwm_config(struct pwm_chip *chip, struct pwm_device
*pwm,
int duty_ns, int period_ns)
{
struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
unsigned long period, duty;
u64 clk_rate, div;
int ret;
clk_rate = clk_get_rate(pc->clk);
/*
* Since period and duty cycle registers have a width of 32
* bits, every possible input period can be obtained using the
* default prescaler value for all practical clock rate values.
*/
div = clk_rate * period_ns;
do_div(div, pc->data->prescaler * NSEC_PER_SEC);
period = div;
div = clk_rate * duty_ns;
do_div(div, pc->data->prescaler * NSEC_PER_SEC);
duty = div;
ret = clk_enable(pc->clk);
if (ret)
return ret;
writel(period, pc->base + pc->data->regs.period);
writel(duty, pc->base + pc->data->regs.duty);
writel(0, pc->base + pc->data->regs.cntr);
clk_disable(pc->clk);
return 0;
}
static int rockchip_pwm_enable(struct pwm_chip *chip, struct pwm_device
*pwm)
{
struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
int ret;
ret = clk_enable(pc->clk);
if (ret)
return ret;
pc->data->set_enable(chip, true);
return 0;
}
static void rockchip_pwm_disable(struct pwm_chip *chip, struct
pwm_device *pwm)
{
struct rockchip_pwm_chip *pc = to_rockchip_pwm_chip(chip);
pc->data->set_enable(chip, false);
clk_disable(pc->clk);
}
static const struct pwm_ops rockchip_pwm_ops = {
.config = rockchip_pwm_config,
.enable = rockchip_pwm_enable,
.disable = rockchip_pwm_disable,
.owner = THIS_MODULE,
};
static const struct rockchip_pwm_data pwm_data_v1 = {
.regs.duty = PWM_HRC,
.regs.period = PWM_LRC,
.regs.cntr = PWM_CNTR,
.regs.ctrl = PWM_CTRL,
.prescaler = PRESCALER,
.set_enable = rockchip_pwm_set_enable_v1,
};
static const struct rockchip_pwm_data pwm_data_v2 = {
.regs.duty = PWM_LRC,
.regs.period = PWM_HRC,
.regs.cntr = PWM_CNTR,
.regs.ctrl = PWM_CTRL,
.prescaler = PRESCALER-1,
.set_enable = rockchip_pwm_set_enable_v2,
};
static const struct rockchip_pwm_data pwm_data_vop = {
.regs.duty = PWM_LRC,
.regs.period = PWM_HRC,
.regs.cntr = PWM_CTRL,
.regs.ctrl = PWM_CNTR,
.prescaler = PRESCALER-1,
.set_enable = rockchip_pwm_set_enable_v2,
};
static const struct of_device_id rockchip_pwm_dt_ids[] = {
{ .compatible = "rockchip,rk2928-pwm", .data = &pwm_data_v1},
{ .compatible = "rockchip,rk3288-pwm", .data = &pwm_data_v2},
{ .compatible = "rockchip,vop-pwm", .data = &pwm_data_vop},
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, rockchip_pwm_dt_ids);
static int rockchip_pwm_probe(struct platform_device *pdev)
{
const struct of_device_id *id;
struct rockchip_pwm_chip *pc;
struct resource *r;
int ret;
id = of_match_device(rockchip_pwm_dt_ids, &pdev->dev);
if (!id)
return -EINVAL;
pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
if (!pc)
return -ENOMEM;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
pc->base = devm_ioremap_resource(&pdev->dev, r);
if (IS_ERR(pc->base))
return PTR_ERR(pc->base);
pc->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(pc->clk))
return PTR_ERR(pc->clk);
ret = clk_prepare(pc->clk);
if (ret)
return ret;
platform_set_drvdata(pdev, pc);
pc->data = id->data;
pc->chip.dev = &pdev->dev;
pc->chip.ops = &rockchip_pwm_ops;
pc->chip.base = -1;
pc->chip.npwm = 1;
ret = pwmchip_add(&pc->chip);
if (ret < 0) {
clk_unprepare(pc->clk);
dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
}
return ret;
}
static int rockchip_pwm_remove(struct platform_device *pdev)
{
struct rockchip_pwm_chip *pc = platform_get_drvdata(pdev);
clk_unprepare(pc->clk);
return pwmchip_remove(&pc->chip);
}
static struct platform_driver rockchip_pwm_driver = {
.driver = {
.name = "rockchip-pwm",
.of_match_table = rockchip_pwm_dt_ids,
},
.probe = rockchip_pwm_probe,
.remove = rockchip_pwm_remove,
};
module_platform_driver(rockchip_pwm_driver);
MODULE_AUTHOR("Beniamino Galvani <b.galvani@...il.com>");
MODULE_DESCRIPTION("Rockchip SoC PWM driver");
MODULE_LICENSE("GPL v2");
-Caesar
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