On Fri, Jul 13, 2012 at 03:05:01PM +0530, Philip, Avinash wrote: > ECAP hardware on AM33XX SOC supports auxiliary PWM (APWM) feature. This > commit adds PWM driver support for ECAP hardware on AM33XX SOC. > > In the ECAP hardware, each PWM pin can also be configured to be in > capture mode. Current implementation only supports PWM mode of > operation. Also, hardware supports sync between multiple PWM pins but > the driver supports simple independent PWM functionality. > > Signed-off-by: Philip, Avinash <avinashphilip@xxxxxx> > Reviewed-by: Vaibhav Bedia <vaibhav.bedia@xxxxxx> > --- > :100644 100644 94e176e... f20b8f2... M drivers/pwm/Kconfig > :100644 100644 5459702... 7dd90ec... M drivers/pwm/Makefile > :000000 100644 0000000... 81efc9e... A drivers/pwm/pwm-ecap.c > drivers/pwm/Kconfig | 10 ++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-ecap.c | 255 ++++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 266 insertions(+), 0 deletions(-) > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index 94e176e..f20b8f2 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -85,4 +85,14 @@ config PWM_VT8500 > To compile this driver as a module, choose M here: the module > will be called pwm-vt8500. > > +config PWM_ECAP > + tristate "ECAP PWM support" > + depends on SOC_AM33XX > + help > + PWM driver support for the ECAP APWM controller found on AM33XX > + TI SOC > + > + To compile this driver as a module, choose M here: the module > + will be called pwm_ecap. > + > endif > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index 5459702..7dd90ec 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -7,3 +7,4 @@ obj-$(CONFIG_PWM_PXA) += pwm-pxa.o > obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o > obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o > obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o > +obj-$(CONFIG_PWM_ECAP) += pwm-ecap.o Both the Kconfig and Makefile should have the entries ordered alphabetically. > diff --git a/drivers/pwm/pwm-ecap.c b/drivers/pwm/pwm-ecap.c > new file mode 100644 > index 0000000..81efc9e > --- /dev/null > +++ b/drivers/pwm/pwm-ecap.c > @@ -0,0 +1,255 @@ > +/* > + * 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 TSCTR 0x00 > +#define CTRPHS 0x04 > +#define CAP1 0x08 > +#define CAP2 0x0C > +#define CAP3 0x10 > +#define CAP4 0x14 > +#define ECCTL1 0x28 These registers are not used. I guess there is some use to list all registers here but on the other hand the majority are unused so they just clutter the driver. > +#define ECCTL2_APWM_POL_LOW BIT(10) This bit is never used. > +#define ECEINT 0x2C > +#define ECFLG 0x2E > +#define ECCLR 0x30 > +#define REVID 0x5c These are unused as well. > + > +#define DRIVER_NAME "ecap" You only use this once when defining the struct platform_driver, so maybe you can just drop it. > + > +struct ecap_pwm_chip { > + struct pwm_chip chip; > + unsigned int clk_rate; > + void __iomem *mmio_base; > + int pwm_period_ns; > + int pwm_duty_ns; > +}; The pwm_period_ns and pwm_duty_ns don't seem to be used at all. Can they be dropped? > + > +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; > + } > + > + pc->pwm_duty_ns = duty_ns; > + pc->pwm_period_ns = period_ns; > + > + pm_runtime_get_sync(pc->chip.dev); > + > + reg_val = readw(pc->mmio_base + ECCTL2); > + > + /* Configure PWM 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; You already set the APWM_MODE bit in .config(), why is it needed here again? Seeing that .disable() clears the bit as well, perhaps leaving it clear in .config() is the better option. > + 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); > + } > +} I wonder whether we want to have something like this in the PWM core at some point. Maybe we should call .disable() automatically when they are freed, or alternatively return -EBUSY if a PWM is freed but still enabled. I think I prefer the latter. For now we can leave this in, because I don't want to make any such core changes for 3.6 now that the merge window is open. > + > +static 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, > +}; This should be "static const pwm_ops ...". > + > +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; The cover letter mentions that the AM335x has 3 instances of the ECAP. Is there any chance that they can be unified in one driver instance (i.e. .npwm = 3?). > + > + r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ecap_reg"); > + if (r == NULL) { You use "if (!ptr)" everywhere else, maybe you should make this consistent? Also the platform_get_resource_byname() is really only useful for devices that have several register regions associated with them. I don't know your hardware in detail, but I doubt that a PWM device has more than one register region. > + 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); > + dev_info(&pdev->dev, "PWM device initialized\n"); I think this can go away. If none of the above errors is shown you can just assume that the PWM was initialized. > + return 0; > +} > + > +static int __devexit ecap_pwm_remove(struct platform_device *pdev) > +{ > + struct ecap_pwm_chip *pc = platform_get_drvdata(pdev); > + struct pwm_device *pwm; > + > + if (WARN_ON(!pc)) > + return -ENODEV; Do you really want to be this verbose? This kind of check is very rare anyway, but explicitly warning about it doesn't seems overkill. I think the check can even be left out, since every possible error that would lead to the driver data not being checked would already cause .probe() to return < 0 and therefore .remove() won't ever be called anyway. > + > + pwm = &pc->chip.pwms[0]; You don't use this variable. Thierry > + pm_runtime_put_sync(&pdev->dev); > + pm_runtime_disable(&pdev->dev); > + pwmchip_remove(&pc->chip); > + return 0; > +} > + > +static struct platform_driver ecap_pwm_driver = { > + .driver = { > + .name = DRIVER_NAME, > + }, > + .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"); > -- > 1.7.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > >
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