| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20130821073659.GN31036@pengutronix.de>
Date: Wed, 21 Aug 2013 09:36:59 +0200
From: Sascha Hauer <s.hauer@...gutronix.de>
To: Xiubo Li <Li.Xiubo@...escale.com>
Cc: r65073@...escale.com, thierry.reding@...il.com,
grant.likely@...aro.org, linux@....linux.org.uk, rob@...dley.net,
ian.campbell@...rix.com, swarren@...dotorg.org,
mark.rutland@....com, pawel.moll@....com, rob.herring@...xeda.com,
linux-arm-kernel@...ts.infradead.org, linux-pwm@...r.kernel.org,
linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
linux-doc@...r.kernel.org, Jingchang Lu <b35083@...escale.com>
Subject: Re: [PATCH 1/4] pwm: add freescale ftm pwm driver support
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 linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists