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pwm: pwm-tiehrpwm: PWM driver support for EHRPWM

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Enhanced high resolution PWM module (EHRPWM) hardware can be used to
generate PWM output over 2 channels. This commit adds PWM driver support
for EHRPWM device present on AM33XX SOC. Current implementation supports
simple PWM functionality.

Reviewed-by: Vaibhav Bedia <vaibhav.bedia@ti.com>
Signed-off-by: Philip, Avinash <avinashphilip@ti.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>
This commit is contained in:
Philip, Avinash 2012-07-25 16:58:19 +05:30 committed by Thierry Reding
parent 8e0cb05b3b
commit 19891b20e7
3 changed files with 422 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

10
drivers/pwm/Kconfig
View file

@ -86,6 +86,16 @@ config PWM_TIECAP
To compile this driver as a module, choose M here: the module
will be called pwm-tiecap.
config PWM_TIEHRPWM
tristate "EHRPWM PWM support"
depends on SOC_AM33XX
help
PWM driver support for the EHRPWM controller found on AM33XX
TI SOC
To compile this driver as a module, choose M here: the module
will be called pwm-tiehrpwm.
config PWM_VT8500
tristate "vt8500 pwm support"
depends on ARCH_VT8500

1
drivers/pwm/Makefile
View file

@ -7,4 +7,5 @@ obj-$(CONFIG_PWM_PXA) += pwm-pxa.o
obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o
obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o
obj-$(CONFIG_PWM_TIEHRPWM) += pwm-tiehrpwm.o
obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o

411
drivers/pwm/pwm-tiehrpwm.c Normal file
View file

@ -0,0 +1,411 @@
/*
* EHRPWM 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/pwm.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/pm_runtime.h>
/* EHRPWM registers and bits definitions */
/* Time base module registers */
#define TBCTL 0x00
#define TBPRD 0x0A
#define TBCTL_RUN_MASK (BIT(15) | BIT(14))
#define TBCTL_STOP_NEXT 0
#define TBCTL_STOP_ON_CYCLE BIT(14)
#define TBCTL_FREE_RUN (BIT(15) | BIT(14))
#define TBCTL_PRDLD_MASK BIT(3)
#define TBCTL_PRDLD_SHDW 0
#define TBCTL_PRDLD_IMDT BIT(3)
#define TBCTL_CLKDIV_MASK (BIT(12) | BIT(11) | BIT(10) | BIT(9) | \
BIT(8) | BIT(7))
#define TBCTL_CTRMODE_MASK (BIT(1) | BIT(0))
#define TBCTL_CTRMODE_UP 0
#define TBCTL_CTRMODE_DOWN BIT(0)
#define TBCTL_CTRMODE_UPDOWN BIT(1)
#define TBCTL_CTRMODE_FREEZE (BIT(1) | BIT(0))
#define TBCTL_HSPCLKDIV_SHIFT 7
#define TBCTL_CLKDIV_SHIFT 10
#define CLKDIV_MAX 7
#define HSPCLKDIV_MAX 7
#define PERIOD_MAX 0xFFFF
/* compare module registers */
#define CMPA 0x12
#define CMPB 0x14
/* Action qualifier module registers */
#define AQCTLA 0x16
#define AQCTLB 0x18
#define AQSFRC 0x1A
#define AQCSFRC 0x1C
#define AQCTL_CBU_MASK (BIT(9) | BIT(8))
#define AQCTL_CBU_FRCLOW BIT(8)
#define AQCTL_CBU_FRCHIGH BIT(9)
#define AQCTL_CBU_FRCTOGGLE (BIT(9) | BIT(8))
#define AQCTL_CAU_MASK (BIT(5) | BIT(4))
#define AQCTL_CAU_FRCLOW BIT(4)
#define AQCTL_CAU_FRCHIGH BIT(5)
#define AQCTL_CAU_FRCTOGGLE (BIT(5) | BIT(4))
#define AQCTL_PRD_MASK (BIT(3) | BIT(2))
#define AQCTL_PRD_FRCLOW BIT(2)
#define AQCTL_PRD_FRCHIGH BIT(3)
#define AQCTL_PRD_FRCTOGGLE (BIT(3) | BIT(2))
#define AQCTL_ZRO_MASK (BIT(1) | BIT(0))
#define AQCTL_ZRO_FRCLOW BIT(0)
#define AQCTL_ZRO_FRCHIGH BIT(1)
#define AQCTL_ZRO_FRCTOGGLE (BIT(1) | BIT(0))
#define AQSFRC_RLDCSF_MASK (BIT(7) | BIT(6))
#define AQSFRC_RLDCSF_ZRO 0
#define AQSFRC_RLDCSF_PRD BIT(6)
#define AQSFRC_RLDCSF_ZROPRD BIT(7)
#define AQSFRC_RLDCSF_IMDT (BIT(7) | BIT(6))
#define AQCSFRC_CSFB_MASK (BIT(3) | BIT(2))
#define AQCSFRC_CSFB_FRCDIS 0
#define AQCSFRC_CSFB_FRCLOW BIT(2)
#define AQCSFRC_CSFB_FRCHIGH BIT(3)
#define AQCSFRC_CSFB_DISSWFRC (BIT(3) | BIT(2))
#define AQCSFRC_CSFA_MASK (BIT(1) | BIT(0))
#define AQCSFRC_CSFA_FRCDIS 0
#define AQCSFRC_CSFA_FRCLOW BIT(0)
#define AQCSFRC_CSFA_FRCHIGH BIT(1)
#define AQCSFRC_CSFA_DISSWFRC (BIT(1) | BIT(0))
#define NUM_PWM_CHANNEL 2 /* EHRPWM channels */
struct ehrpwm_pwm_chip {
struct pwm_chip chip;
unsigned int clk_rate;
void __iomem *mmio_base;
};
static inline struct ehrpwm_pwm_chip *to_ehrpwm_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct ehrpwm_pwm_chip, chip);
}
static void ehrpwm_write(void *base, int offset, unsigned int val)
{
writew(val & 0xFFFF, base + offset);
}
static void ehrpwm_modify(void *base, int offset,
unsigned short mask, unsigned short val)
{
unsigned short regval;
regval = readw(base + offset);
regval &= ~mask;
regval |= val & mask;
writew(regval, base + offset);
}
/**
* set_prescale_div - Set up the prescaler divider function
* @rqst_prescaler: prescaler value min
* @prescale_div: prescaler value set
* @tb_clk_div: Time Base Control prescaler bits
*/
static int set_prescale_div(unsigned long rqst_prescaler,
unsigned short *prescale_div, unsigned short *tb_clk_div)
{
unsigned int clkdiv, hspclkdiv;
for (clkdiv = 0; clkdiv <= CLKDIV_MAX; clkdiv++) {
for (hspclkdiv = 0; hspclkdiv <= HSPCLKDIV_MAX; hspclkdiv++) {
/*
* calculations for prescaler value :
* prescale_div = HSPCLKDIVIDER * CLKDIVIDER.
* HSPCLKDIVIDER = 2 ** hspclkdiv
* CLKDIVIDER = (1), if clkdiv == 0 *OR*
* (2 * clkdiv), if clkdiv != 0
*
* Configure prescale_div value such that period
* register value is less than 65535.
*/
*prescale_div = (1 << clkdiv) *
(hspclkdiv ? (hspclkdiv * 2) : 1);
if (*prescale_div > rqst_prescaler) {
*tb_clk_div = (clkdiv << TBCTL_CLKDIV_SHIFT) |
(hspclkdiv << TBCTL_HSPCLKDIV_SHIFT);
return 0;
}
}
}
return 1;
}
static void configure_chans(struct ehrpwm_pwm_chip *pc, int chan,
unsigned long duty_cycles)
{
int cmp_reg, aqctl_reg;
unsigned short aqctl_val, aqctl_mask;
/*
* Channels can be configured from action qualifier module.
* Channel 0 configured with compare A register and for
* up-counter mode.
* Channel 1 configured with compare B register and for
* up-counter mode.
*/
if (chan == 1) {
aqctl_reg = AQCTLB;
cmp_reg = CMPB;
/* Configure PWM Low from compare B value */
aqctl_val = AQCTL_CBU_FRCLOW;
aqctl_mask = AQCTL_CBU_MASK;
} else {
cmp_reg = CMPA;
aqctl_reg = AQCTLA;
/* Configure PWM Low from compare A value*/
aqctl_val = AQCTL_CAU_FRCLOW;
aqctl_mask = AQCTL_CAU_MASK;
}
/* Configure PWM High from period value and zero value */
aqctl_val |= AQCTL_PRD_FRCHIGH | AQCTL_ZRO_FRCHIGH;
aqctl_mask |= AQCTL_PRD_MASK | AQCTL_ZRO_MASK;
ehrpwm_modify(pc->mmio_base, aqctl_reg, aqctl_mask, aqctl_val);
ehrpwm_write(pc->mmio_base, cmp_reg, duty_cycles);
}
/*
* period_ns = 10^9 * (ps_divval * period_cycles) / PWM_CLK_RATE
* duty_ns = 10^9 * (ps_divval * duty_cycles) / PWM_CLK_RATE
*/
static int ehrpwm_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
unsigned long long c;
unsigned long period_cycles, duty_cycles;
unsigned short ps_divval, tb_divval;
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;
}
/* Configure clock prescaler to support Low frequency PWM wave */
if (set_prescale_div(period_cycles/PERIOD_MAX, &ps_divval,
&tb_divval)) {
dev_err(chip->dev, "Unsupported values\n");
return -EINVAL;
}
pm_runtime_get_sync(chip->dev);
/* Update clock prescaler values */
ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CLKDIV_MASK, tb_divval);
/* Update period & duty cycle with presacler division */
period_cycles = period_cycles / ps_divval;
duty_cycles = duty_cycles / ps_divval;
/* Configure shadow loading on Period register */
ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_PRDLD_MASK, TBCTL_PRDLD_SHDW);
ehrpwm_write(pc->mmio_base, TBPRD, period_cycles);
/* Configure ehrpwm counter for up-count mode */
ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_CTRMODE_MASK,
TBCTL_CTRMODE_UP);
/* Configure the channel for duty cycle */
configure_chans(pc, pwm->hwpwm, duty_cycles);
pm_runtime_put_sync(chip->dev);
return 0;
}
static int ehrpwm_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
unsigned short aqcsfrc_val, aqcsfrc_mask;
/* Leave clock enabled on enabling PWM */
pm_runtime_get_sync(chip->dev);
/* Disabling Action Qualifier on PWM output */
if (pwm->hwpwm) {
aqcsfrc_val = AQCSFRC_CSFB_FRCDIS;
aqcsfrc_mask = AQCSFRC_CSFB_MASK;
} else {
aqcsfrc_val = AQCSFRC_CSFA_FRCDIS;
aqcsfrc_mask = AQCSFRC_CSFA_MASK;
}
/* Changes to shadow mode */
ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
AQSFRC_RLDCSF_ZRO);
ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);
/* Enable time counter for free_run */
ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_RUN_MASK, TBCTL_FREE_RUN);
return 0;
}
static void ehrpwm_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct ehrpwm_pwm_chip *pc = to_ehrpwm_pwm_chip(chip);
unsigned short aqcsfrc_val, aqcsfrc_mask;
/* Action Qualifier puts PWM output low forcefully */
if (pwm->hwpwm) {
aqcsfrc_val = AQCSFRC_CSFB_FRCLOW;
aqcsfrc_mask = AQCSFRC_CSFB_MASK;
} else {
aqcsfrc_val = AQCSFRC_CSFA_FRCLOW;
aqcsfrc_mask = AQCSFRC_CSFA_MASK;
}
/*
* Changes to immediate action on Action Qualifier. This puts
* Action Qualifier control on PWM output from next TBCLK
*/
ehrpwm_modify(pc->mmio_base, AQSFRC, AQSFRC_RLDCSF_MASK,
AQSFRC_RLDCSF_IMDT);
ehrpwm_modify(pc->mmio_base, AQCSFRC, aqcsfrc_mask, aqcsfrc_val);
/* Stop Time base counter */
ehrpwm_modify(pc->mmio_base, TBCTL, TBCTL_RUN_MASK, TBCTL_STOP_NEXT);
/* Disable clock on PWM disable */
pm_runtime_put_sync(chip->dev);
}
static void ehrpwm_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 ehrpwm_pwm_ops = {
.free = ehrpwm_pwm_free,
.config = ehrpwm_pwm_config,
.enable = ehrpwm_pwm_enable,
.disable = ehrpwm_pwm_disable,
.owner = THIS_MODULE,
};
static int __devinit ehrpwm_pwm_probe(struct platform_device *pdev)
{
int ret;
struct resource *r;
struct clk *clk;
struct ehrpwm_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 = &ehrpwm_pwm_ops;
pc->chip.base = -1;
pc->chip.npwm = NUM_PWM_CHANNEL;
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) {
dev_err(&pdev->dev, "failed to ioremap() registers\n");
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 ehrpwm_pwm_remove(struct platform_device *pdev)
{
struct ehrpwm_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 ehrpwm_pwm_driver = {
.driver = {
.name = "ehrpwm",
},
.probe = ehrpwm_pwm_probe,
.remove = __devexit_p(ehrpwm_pwm_remove),
};
module_platform_driver(ehrpwm_pwm_driver);
MODULE_DESCRIPTION("EHRPWM PWM driver");
MODULE_AUTHOR("Texas Instruments");
MODULE_LICENSE("GPL");