/*
* ECAP PWM driver
*
* Copyright (C) 2012 Texas Instruments, Inc. - http://www.ti.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; 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/pm_runtime.h>
#include <linux/pwm.h>
/* ECAP registers and bits definitions */
#define CAP1 0x08
#define CAP2 0x0C
#define CAP3 0x10
#define CAP4 0x14
#define ECCTL2 0x2A
#define ECCTL2_APWM_MODE BIT(9)
#define ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6))
#define ECCTL2_TSCTR_FREERUN BIT(4)
struct ecap_pwm_chip {
struct pwm_chip chip;
unsigned int clk_rate;
void __iomem *mmio_base;
};
static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct ecap_pwm_chip, chip);
}
/*
* period_ns = 10^9 * period_cycles / PWM_CLK_RATE
* duty_ns = 10^9 * duty_cycles / PWM_CLK_RATE
*/
static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
unsigned long long c;
unsigned long period_cycles, duty_cycles;
unsigned int reg_val;
if (period_ns < 0 || duty_ns < 0 || period_ns > NSEC_PER_SEC)
return -ERANGE;
c = pc->clk_rate;
c = c * period_ns;
do_div(c, NSEC_PER_SEC);
period_cycles = (unsigned long)c;
if (period_cycles < 1) {
period_cycles = 1;
duty_cycles = 1;
} else {
c = pc->clk_rate;
c = c * duty_ns;
do_div(c, NSEC_PER_SEC);
duty_cycles = (unsigned long)c;
}
pm_runtime_get_sync(pc->chip.dev);
reg_val = readw(pc->mmio_base + ECCTL2);
/* Configure APWM mode & disable sync option */
reg_val |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA;
writew(reg_val, pc->mmio_base + ECCTL2);
if (!test_bit(PWMF_ENABLED, &pwm->flags)) {
/* Update active registers if not running */
writel(duty_cycles, pc->mmio_base + CAP2);
writel(period_cycles, pc->mmio_base + CAP1);
} else {
/*
* Update shadow registers to configure period and
* compare values. This helps current PWM period to
* complete on reconfiguring
*/
writel(duty_cycles, pc->mmio_base + CAP4);
writel(period_cycles, pc->mmio_base + CAP3);
}
pm_runtime_put_sync(pc->chip.dev);
return 0;
}
static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
unsigned int reg_val;
/* Leave clock enabled on enabling PWM */
pm_runtime_get_sync(pc->chip.dev);
/*
* Enable 'Free run Time stamp counter mode' to start counter
* and 'APWM mode' to enable APWM output
*/
reg_val = readw(pc->mmio_base + ECCTL2);
reg_val |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE;
writew(reg_val, pc->mmio_base + ECCTL2);
return 0;
}
static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
unsigned int reg_val;
/*
* Disable 'Free run Time stamp counter mode' to stop counter
* and 'APWM mode' to put APWM output to low
*/
reg_val = readw(pc->mmio_base + ECCTL2);
reg_val &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE);
writew(reg_val, pc->mmio_base + ECCTL2);
/* Disable clock on PWM disable */
pm_runtime_put_sync(pc->chip.dev);
}
static void ecap_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
if (test_bit(PWMF_ENABLED, &pwm->flags)) {
dev_warn(chip->dev, "Removing PWM device without disabling\n");
pm_runtime_put_sync(chip->dev);
}
}
static const struct pwm_ops ecap_pwm_ops = {
.free = ecap_pwm_free,
.config = ecap_pwm_config,
.enable = ecap_pwm_enable,
.disable = ecap_pwm_disable,
.owner = THIS_MODULE,
};
static int __devinit ecap_pwm_probe(struct platform_device *pdev)
{
int ret;
struct resource *r;
struct clk *clk;
struct ecap_pwm_chip *pc;
pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
if (!pc) {
dev_err(&pdev->dev, "failed to allocate memory\n");
return -ENOMEM;
}
clk = devm_clk_get(&pdev->dev, "fck");
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "failed to get clock\n");
return PTR_ERR(clk);
}
pc->clk_rate = clk_get_rate(clk);
if (!pc->clk_rate) {
dev_err(&pdev->dev, "failed to get clock rate\n");
return -EINVAL;
}
pc->chip.dev = &pdev->dev;
pc->chip.ops = &ecap_pwm_ops;
pc->chip.base = -1;
pc->chip.npwm = 1;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!r) {
dev_err(&pdev->dev, "no memory resource defined\n");
return -ENODEV;
}
pc->mmio_base = devm_request_and_ioremap(&pdev->dev, r);
if (!pc->mmio_base)
return -EADDRNOTAVAIL;
ret = pwmchip_add(&pc->chip);
if (ret < 0) {
dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
return ret;
}
pm_runtime_enable(&pdev->dev);
platform_set_drvdata(pdev, pc);
return 0;
}
static int __devexit ecap_pwm_remove(struct platform_device *pdev)
{
struct ecap_pwm_chip *pc = platform_get_drvdata(pdev);
pm_runtime_put_sync(&pdev->dev);
pm_runtime_disable(&pdev->dev);
return pwmchip_remove(&pc->chip);
}
static struct platform_driver ecap_pwm_driver = {
.driver = {
.name = "ecap",
},
.probe = ecap_pwm_probe,
.remove = __devexit_p(ecap_pwm_remove),
};
module_platform_driver(ecap_pwm_driver);
MODULE_DESCRIPTION("ECAP PWM driver");
MODULE_AUTHOR("Texas Instruments");
MODULE_LICENSE("GPL");
