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pwm: Add Broadcom BCM7038 PWM controller support 

Add support for the BCM7038-style PWM controller found in all BCM7xxx STB SoCs.
This controller has a hardcoded 2 channels per controller, and cascades a
variable frequency generator on top of a fixed frequency generator which offers
a range of a 148ns period all the way to ~622ms periods.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Florian Fainelli 2015-09-14 16:47:06 -07:00 committed by Thierry Reding
parent 9495525e51
commit 3a9f595702
3 changed files with 354 additions and 0 deletions
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10
drivers/pwm/Kconfig
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@ -110,6 +110,16 @@ config PWM_BFIN
To compile this driver as a module, choose M here: the module
will be called pwm-bfin.
config PWM_BRCMSTB
tristate "Broadcom STB PWM support"
depends on ARCH_BRCMSTB || BMIPS_GENERIC
help
Generic PWM framework driver for the Broadcom Set-top-Box
SoCs (BCM7xxx).
To compile this driver as a module, choose M Here: the module
will be called pwm-brcmstb.c.
config PWM_CLPS711X
tristate "CLPS711X PWM support"
depends on ARCH_CLPS711X || COMPILE_TEST

1
drivers/pwm/Makefile
View File

@ -8,6 +8,7 @@ obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o
obj-$(CONFIG_PWM_BERLIN) += pwm-berlin.o
obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
obj-$(CONFIG_PWM_BRCMSTB) += pwm-brcmstb.o
obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
obj-$(CONFIG_PWM_CRC) += pwm-crc.o
obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o

343
drivers/pwm/pwm-brcmstb.c Normal file
View File

@ -0,0 +1,343 @@
/*
* Broadcom BCM7038 PWM driver
* Author: Florian Fainelli
*
* Copyright (C) 2015 Broadcom Corporation
*
* 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; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/clk.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/spinlock.h>
#define PWM_CTRL 0x00
#define CTRL_START BIT(0)
#define CTRL_OEB BIT(1)
#define CTRL_FORCE_HIGH BIT(2)
#define CTRL_OPENDRAIN BIT(3)
#define CTRL_CHAN_OFFS 4
#define PWM_CTRL2 0x04
#define CTRL2_OUT_SELECT BIT(0)
#define PWM_CH_SIZE 0x8
#define PWM_CWORD_MSB(ch) (0x08 + ((ch) * PWM_CH_SIZE))
#define PWM_CWORD_LSB(ch) (0x0c + ((ch) * PWM_CH_SIZE))
/* Number of bits for the CWORD value */
#define CWORD_BIT_SIZE 16
/*
* Maximum control word value allowed when variable-frequency PWM is used as a
* clock for the constant-frequency PMW.
*/
#define CONST_VAR_F_MAX 32768
#define CONST_VAR_F_MIN 1
#define PWM_ON(ch) (0x18 + ((ch) * PWM_CH_SIZE))
#define PWM_ON_MIN 1
#define PWM_PERIOD(ch) (0x1c + ((ch) * PWM_CH_SIZE))
#define PWM_PERIOD_MIN 0
#define PWM_ON_PERIOD_MAX 0xff
struct brcmstb_pwm {
void __iomem *base;
spinlock_t lock;
struct clk *clk;
struct pwm_chip chip;
};
static inline u32 brcmstb_pwm_readl(struct brcmstb_pwm *p,
unsigned int offset)
{
if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
return __raw_readl(p->base + offset);
else
return readl_relaxed(p->base + offset);
}
static inline void brcmstb_pwm_writel(struct brcmstb_pwm *p, u32 value,
unsigned int offset)
{
if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
__raw_writel(value, p->base + offset);
else
writel_relaxed(value, p->base + offset);
}
static inline struct brcmstb_pwm *to_brcmstb_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct brcmstb_pwm, chip);
}
/*
* Fv is derived from the variable frequency output. The variable frequency
* output is configured using this formula:
*
* W = cword, if cword < 2 ^ 15 else 16-bit 2's complement of cword
*
* Fv = W x 2 ^ -16 x 27Mhz (reference clock)
*
* The period is: (period + 1) / Fv and "on" time is on / (period + 1)
*
* The PWM core framework specifies that the "duty_ns" parameter is in fact the
* "on" time, so this translates directly into our HW programming here.
*/
static int brcmstb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
unsigned long pc, dc, cword = CONST_VAR_F_MAX;
unsigned int channel = pwm->hwpwm;
u32 value;
/*
* If asking for a duty_ns equal to period_ns, we need to substract
* the period value by 1 to make it shorter than the "on" time and
* produce a flat 100% duty cycle signal, and max out the "on" time
*/
if (duty_ns == period_ns) {
dc = PWM_ON_PERIOD_MAX;
pc = PWM_ON_PERIOD_MAX - 1;
goto done;
}
while (1) {
u64 rate, tmp;
/*
* Calculate the base rate from base frequency and current
* cword
*/
rate = (u64)clk_get_rate(p->clk) * (u64)cword;
do_div(rate, 1 << CWORD_BIT_SIZE);
tmp = period_ns * rate;
do_div(tmp, NSEC_PER_SEC);
pc = tmp;
tmp = (duty_ns + 1) * rate;
do_div(tmp, NSEC_PER_SEC);
dc = tmp;
/*
* We can be called with separate duty and period updates,
* so do not reject dc == 0 right away
*/
if (pc == PWM_PERIOD_MIN || (dc < PWM_ON_MIN && duty_ns))
return -EINVAL;
/* We converged on a calculation */
if (pc <= PWM_ON_PERIOD_MAX && dc <= PWM_ON_PERIOD_MAX)
break;
/*
* The cword needs to be a power of 2 for the variable
* frequency generator to output a 50% duty cycle variable
* frequency which is used as input clock to the fixed
* frequency generator.
*/
cword >>= 1;
/*
* Desired periods are too large, we do not have a divider
* for them
*/
if (cword < CONST_VAR_F_MIN)
return -EINVAL;
}
done:
/*
* Configure the defined "cword" value to have the variable frequency
* generator output a base frequency for the constant frequency
* generator to derive from.
*/
spin_lock(&p->lock);
brcmstb_pwm_writel(p, cword >> 8, PWM_CWORD_MSB(channel));
brcmstb_pwm_writel(p, cword & 0xff, PWM_CWORD_LSB(channel));
/* Select constant frequency signal output */
value = brcmstb_pwm_readl(p, PWM_CTRL2);
value |= CTRL2_OUT_SELECT << (channel * CTRL_CHAN_OFFS);
brcmstb_pwm_writel(p, value, PWM_CTRL2);
/* Configure on and period value */
brcmstb_pwm_writel(p, pc, PWM_PERIOD(channel));
brcmstb_pwm_writel(p, dc, PWM_ON(channel));
spin_unlock(&p->lock);
return 0;
}
static inline void brcmstb_pwm_enable_set(struct brcmstb_pwm *p,
unsigned int channel, bool enable)
{
unsigned int shift = channel * CTRL_CHAN_OFFS;
u32 value;
spin_lock(&p->lock);
value = brcmstb_pwm_readl(p, PWM_CTRL);
if (enable) {
value &= ~(CTRL_OEB << shift);
value |= (CTRL_START | CTRL_OPENDRAIN) << shift;
} else {
value &= ~((CTRL_START | CTRL_OPENDRAIN) << shift);
value |= CTRL_OEB << shift;
}
brcmstb_pwm_writel(p, value, PWM_CTRL);
spin_unlock(&p->lock);
}
static int brcmstb_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
brcmstb_pwm_enable_set(p, pwm->hwpwm, true);
return 0;
}
static void brcmstb_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
brcmstb_pwm_enable_set(p, pwm->hwpwm, false);
}
static const struct pwm_ops brcmstb_pwm_ops = {
.config = brcmstb_pwm_config,
.enable = brcmstb_pwm_enable,
.disable = brcmstb_pwm_disable,
.owner = THIS_MODULE,
};
static const struct of_device_id brcmstb_pwm_of_match[] = {
{ .compatible = "brcm,bcm7038-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, brcmstb_pwm_of_match);
static int brcmstb_pwm_probe(struct platform_device *pdev)
{
struct brcmstb_pwm *p;
struct resource *res;
int ret;
p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
if (!p)
return -ENOMEM;
spin_lock_init(&p->lock);
p->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(p->clk)) {
dev_err(&pdev->dev, "failed to obtain clock\n");
return PTR_ERR(p->clk);
}
ret = clk_prepare_enable(p->clk);
if (ret < 0) {
dev_err(&pdev->dev, "failed to enable clock: %d\n", ret);
return ret;
}
platform_set_drvdata(pdev, p);
p->chip.dev = &pdev->dev;
p->chip.ops = &brcmstb_pwm_ops;
p->chip.base = -1;
p->chip.npwm = 2;
p->chip.can_sleep = true;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
p->base = devm_ioremap_resource(&pdev->dev, res);
if (!p->base) {
ret = -ENOMEM;
goto out_clk;
}
ret = pwmchip_add(&p->chip);
if (ret) {
dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
goto out_clk;
}
return 0;
out_clk:
clk_disable_unprepare(p->clk);
return ret;
}
static int brcmstb_pwm_remove(struct platform_device *pdev)
{
struct brcmstb_pwm *p = platform_get_drvdata(pdev);
int ret;
ret = pwmchip_remove(&p->chip);
clk_disable_unprepare(p->clk);
return ret;
}
#ifdef CONFIG_PM_SLEEP
static int brcmstb_pwm_suspend(struct device *dev)
{
struct brcmstb_pwm *p = dev_get_drvdata(dev);
clk_disable(p->clk);
return 0;
}
static int brcmstb_pwm_resume(struct device *dev)
{
struct brcmstb_pwm *p = dev_get_drvdata(dev);
clk_enable(p->clk);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(brcmstb_pwm_pm_ops, brcmstb_pwm_suspend,
brcmstb_pwm_resume);
static struct platform_driver brcmstb_pwm_driver = {
.probe = brcmstb_pwm_probe,
.remove = brcmstb_pwm_remove,
.driver = {
.name = "pwm-brcmstb",
.of_match_table = brcmstb_pwm_of_match,
.pm = &brcmstb_pwm_pm_ops,
},
};
module_platform_driver(brcmstb_pwm_driver);
MODULE_AUTHOR("Florian Fainelli <f.fainelli@gmail.com>");
MODULE_DESCRIPTION("Broadcom STB PWM driver");
MODULE_ALIAS("platform:pwm-brcmstb");
MODULE_LICENSE("GPL");