On Wed, Aug 21, 2013 at 11:07:39AM +0800, Xiubo Li wrote: > + > +#define FTM_CSC_BASE 0x0C > +#define FTM_CSC(_CHANNEL) \ > + (FTM_CSC_BASE + (_CHANNEL * 0x08)) I see this more and more in FSL code. This is unsafe! Consider what happens when we call FTM_CSC(1 + 1). The result is certainly not what you want. > + > +static int fsl_pwm_request_channel(struct pwm_chip *chip, > + struct pwm_device *pwm) > +{ > + int ret = 0; No need to initialize this variable. > + struct fsl_pwm_chip *fpc; > + > + fpc = to_fsl_chip(chip); > + > + ret = clk_prepare_enable(fpc->clk); > + if (ret) { > + dev_err(&fpc->pdev->dev, > + "failed to clk_prepare_enable " > + "ftm pwm module clock : %d\n", > + ret); Just return ret. We do not need a message for each failed function in the kernel. > + return ret; > + } > + > + return 0; > +} > + > +static int fsl_updata_config(struct fsl_pwm_chip *fpc, > + struct pwm_device *pwm) > +{ > + int i; > + unsigned long reg, cntin = FTM_CNTIN_VAL; > + struct pwm_chip *chip = &fpc->chip; > + > + reg = readl(fpc->base + FTM_SC); > + reg &= ~(FTMSC_CPWMS); > + reg |= (fpc->cpwm ? FTMSC_CPWMS : 0x00); > + writel(reg, fpc->base + FTM_SC); > + > + if (pwm && fpc->cpwm) { > + writel(fpc->fpwms[pwm->hwpwm].period_cycles / 2 + cntin, > + fpc->base + FTM_MOD); > + writel(fpc->fpwms[pwm->hwpwm].duty_cycles / 2 + cntin, > + fpc->base + FTM_CV(pwm->hwpwm)); > + } else if (pwm) { > + writel(fpc->fpwms[pwm->hwpwm].period_cycles + cntin - 1, > + fpc->base + FTM_MOD); > + writel(fpc->fpwms[pwm->hwpwm].duty_cycles + cntin, > + fpc->base + FTM_CV(pwm->hwpwm)); > + } > + > + if (pwm) > + return 0; > + > + for (i = 0; i < chip->npwm; i++) { > + if (!test_bit(PWMF_ENABLED, &chip->pwms[i].flags)) > + continue; > + if (fpc->cpwm) { > + writel(fpc->fpwms[i].period_cycles / 2 + cntin, > + fpc->base + FTM_MOD); > + writel(fpc->fpwms[i].duty_cycles / 2 + cntin, > + fpc->base + FTM_CV(i)); > + } else { > + writel(fpc->fpwms[i].period_cycles + cntin - 1, > + fpc->base + FTM_MOD); > + writel(fpc->fpwms[i].duty_cycles + cntin, > + fpc->base + FTM_CV(i)); > + } > + } > + The behaviour of this function is completely different for pwm == NULL and pwm != NULL. This indicates that it should really be two functions. This probably makes the intention of this code much clearer. > +static int fsl_pwm_config_channel(struct pwm_chip *chip, > + struct pwm_device *pwm, > + int duty_ns, > + int period_ns) > +{ > + unsigned long period_cycles, duty_cycles; > + struct fsl_pwm_chip *fpc; > + > + fpc = to_fsl_chip(chip); > + > + if (WARN_ON(!test_bit(PWMF_REQUESTED, &pwm->flags))) > + return -ESHUTDOWN; > + > + period_cycles = fsl_rate_to_cycles(fpc, period_ns); > + if (period_cycles > 0xFFFF) { > + dev_warn(&fpc->pdev->dev, > + "required PWM period cycles(%lu) " > + "overflow 16-bits counter!\n", > + period_cycles); > + period_cycles = 0xFFFF; If you can't fulfill the requirements you have to return an error. It's the caller that needs to know the failure. The caller can't read read the syslog. > +static int fsl_pwm_enable_channel(struct pwm_chip *chip, > + struct pwm_device *pwm) > +{ > + int ret; > + unsigned long reg; > + struct fsl_pwm_chip *fpc; > + struct pinctrl_state *pins_state; > + const char *statename; > + > + fpc = to_fsl_chip(chip); > + > + if (WARN_ON(!test_bit(PWMF_REQUESTED, &pwm->flags))) > + return -ESHUTDOWN; > + > + statename = kasprintf(GFP_KERNEL, "en%d", pwm->hwpwm); > + pins_state = pinctrl_lookup_state(fpc->pinctrl, > + statename); > + /* enable pins to be muxed in and configured */ > + if (!IS_ERR(pins_state)) { > + ret = pinctrl_select_state(fpc->pinctrl, pins_state); > + if (ret) > + dev_warn(&fpc->pdev->dev, > + "could not set default pins\n"); Why do you need to manipulate the pinctrl to en/disable a channel? > +static ssize_t fsl_pwm_cpwm_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, > + size_t count) > +{ > + int ret; > + unsigned int val; > + struct fsl_pwm_chip *fpc; > + > + fpc = dev_get_drvdata(dev); > + > + ret = kstrtouint(buf, 0, &val); > + if (ret) > + return ret; > + > + mutex_lock(&fpc->lock); > + if (!!(val) != !!(fpc->cpwm)) { > + fpc->cpwm = !!val; > + fsl_updata_config(fpc, NULL); > + } > + mutex_unlock(&fpc->lock); > + > + return count; > +} What is this cpwm thingy? > + > +static DEVICE_ATTR(cpwm, S_IRUGO | S_IWUSR | S_IWGRP, > + fsl_pwm_cpwm_show, fsl_pwm_cpwm_store); > + > +static struct attribute *fsl_pwm_attrs[] = { > + &dev_attr_cpwm.attr, > + NULL > +}; > + > +static int fsl_pwm_probe(struct platform_device *pdev) > +{ > + int ret = 0; > + struct fsl_pwm_chip *fpc; > + struct resource *res; > + > + fpc = devm_kzalloc(&pdev->dev, sizeof(*fpc), GFP_KERNEL); > + if (!fpc) { > + dev_err(&pdev->dev, > + "failed to allocate memory\n"); Drop this message. You'll never see it. > + return -ENOMEM; > + } > + > + mutex_init(&fpc->lock); > + > + fpc->pdev = pdev; > + > + ret = fsl_pwm_parse_dt(fpc); > + if (ret < 0) > + return ret; > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + fpc->base = devm_ioremap_resource(&pdev->dev, res); > + if (IS_ERR(fpc->base)) { > + dev_err(&pdev->dev, > + "failed to ioremap() registers\n"); > + ret = PTR_ERR(fpc->base); > + return ret; > + } > + > + fpc->chip.dev = &pdev->dev; > + fpc->chip.ops = &fsl_pwm_ops; > + fpc->chip.of_xlate = of_pwm_xlate_with_flags; > + fpc->chip.of_pwm_n_cells = 3; > + fpc->chip.base = -1; > + > + ret = pwmchip_add(&fpc->chip); > + if (ret < 0) { > + dev_err(&pdev->dev, > + "failed to add ftm0 pwm chip %d\n", > + ret); > + return ret; > + } You can only add the PWM when you grabbed all resources, not before this. > + > + fpc->clk = devm_clk_get(&pdev->dev, "ftm0"); > + if (IS_ERR(fpc->clk)) { > + ret = PTR_ERR(fpc->clk); > + dev_err(&pdev->dev, > + "failed to get ftm0's module clock %d\n", > + ret); > + return ret; > + } > + > + fpc->pinctrl = devm_pinctrl_get(&pdev->dev); > + if (IS_ERR(fpc->pinctrl)) { > + ret = PTR_ERR(fpc->pinctrl); > + return ret; > + } > + > + ret = sysfs_create_group(&pdev->dev.kobj, > + &fsl_pwm_attr_group); > + if (ret) { > + dev_err(&pdev->dev, > + "Failed to create sysfs " > + "attributes, err: %d\n", > + ret); > + return ret; > + } > + > + platform_set_drvdata(pdev, fpc); > + > + return 0; > +} > + > +static int fsl_pwm_remove(struct platform_device *pdev) > +{ > + struct fsl_pwm_chip *fpc; > + > + fpc = platform_get_drvdata(pdev); > + if (fpc == NULL) > + return -ENODEV; This won't happen. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html