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Message-ID: <20121109075219.GA22224@avionic-0098.mockup.avionic-design.de>
Date: Fri, 9 Nov 2012 08:52:19 +0100
From: Thierry Reding <thierry.reding@...onic-design.de>
To: "Philip, Avinash" <avinashphilip@...com>
Cc: paul@...an.com, tony@...mide.com, linux@....linux.org.uk,
b-cousson@...com, hvaibhav@...com, anilkumar@...com,
linux-kernel@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
linux-doc@...r.kernel.org, linux-omap@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org, nsekhar@...com,
gururaja.hebbar@...com, vaibhav.bedia@...com,
Rob Herring <rob.herring@...xeda.com>,
Rob Landley <rob@...dley.net>
Subject: Re: [PATCH v2 04/10] pwm: pwm-tiecap: Add device-tree binding
support for APWM driver
On Thu, Nov 08, 2012 at 01:23:11PM +0530, Philip, Avinash wrote:
> This patch
> 1. Add support for device-tree binding for ECAP APWM driver.
> 2. Set size of pwm-cells set to 3 to support PWM channel number, PWM
> period & polarity configuration from device tree.
> 3. Add enable/disable clock gating in PWM subsystem common config space.
> 4. When here set .owner member in platform_driver structure to
> THIS_MODULE.
>
> Signed-off-by: Philip, Avinash <avinashphilip@...com>
> Cc: Grant Likely <grant.likely@...retlab.ca>
> Cc: Rob Herring <rob.herring@...xeda.com>
> Cc: Rob Landley <rob@...dley.net>
> ---
> Changes since v1:
> - Add separate patch for pinctrl support
> - Add conditional check for PWM subsystem clock enable.
> - Combined with HWMOD changes & DT bindings.
> - Remove the custom of xlate support.
>
> :000000 100644 0000000... fe24cac... A Documentation/devicetree/bindings/pwm/pwm-tiecap.txt
> :100644 100644 d6d4cf0... 0d43266... M drivers/pwm/pwm-tiecap.c
> .../devicetree/bindings/pwm/pwm-tiecap.txt | 22 +++++++++
> drivers/pwm/pwm-tiecap.c | 48 +++++++++++++++++++-
> 2 files changed, 69 insertions(+), 1 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/pwm/pwm-tiecap.txt b/Documentation/devicetree/bindings/pwm/pwm-tiecap.txt
> new file mode 100644
> index 0000000..fe24cac
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/pwm/pwm-tiecap.txt
> @@ -0,0 +1,22 @@
> +TI SOC ECAP based APWM controller
> +
> +Required properties:
> +- compatible: Must be "ti,am33xx-ecap"
> +- #pwm-cells: Should be 3. Number of cells being used to specify PWM property.
> + First cell specifies the per-chip index of the PWM to use, the second
> + cell is the period cycle in nanoseconds and bit 0 in the third cell is
I think this should be "period in nanoseconds". I haven't heard "period
cycle" before.
> + used to encode the polarity of PWM output.
Maybe you should explicitly say how this is encoded.
> +- reg: physical base address and size of the registers map.
> +
> +Optional properties:
> +- ti,hwmods: Name of the hwmod associated to the ECAP:
> + "ecap<x>", <x> being the 0-based instance number from the HW spec
> +
> +Example:
> +
> +ecap0: ecap@0 {
> + compatible = "ti,am33xx-ecap";
> + #pwm-cells = <3>;
> + reg = <0x48300100 0x80>;
> + ti,hwmods = "ecap0";
> +};
> diff --git a/drivers/pwm/pwm-tiecap.c b/drivers/pwm/pwm-tiecap.c
> index d6d4cf0..0d43266 100644
> --- a/drivers/pwm/pwm-tiecap.c
> +++ b/drivers/pwm/pwm-tiecap.c
> @@ -25,6 +25,9 @@
> #include <linux/clk.h>
> #include <linux/pm_runtime.h>
> #include <linux/pwm.h>
> +#include <linux/of_device.h>
> +
> +#include "tipwmss.h"
>
> /* ECAP registers and bits definitions */
> #define CAP1 0x08
> @@ -37,6 +40,13 @@
> #define ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6))
> #define ECCTL2_TSCTR_FREERUN BIT(4)
>
> +#define ECAPCLK_EN BIT(0)
> +#define ECAPCLK_STOP_REQ BIT(1)
This one doesn't seem to align with the rest. Also, why is bit 0 called
_EN and bit 1 _STOP_REQ? Couldn't they be made more consistent, i.e.
_START and _STOP? Or _ENABLE and _DISABLE?
> +
> +#define ECAPCLK_EN_ACK BIT(0)
> +
> +#define PWM_CELL_SIZE 3
You don't need a define for this.
> +
> struct ecap_pwm_chip {
> struct pwm_chip chip;
> unsigned int clk_rate;
> @@ -184,6 +194,16 @@ static const struct pwm_ops ecap_pwm_ops = {
> .owner = THIS_MODULE,
> };
>
> +#ifdef CONFIG_OF
> +static const struct of_device_id ecap_of_match[] = {
> + {
> + .compatible = "ti,am33xx-ecap",
> + },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, ecap_of_match);
> +#endif
> +
I'm not sure if I remember correctly, but wasn't AM33xx support supposed
to be DT only? In that case you don't need the CONFIG_OF guards.
> static int __devinit ecap_pwm_probe(struct platform_device *pdev)
__devinit can go away.
> {
> int ret;
> @@ -211,6 +231,7 @@ static int __devinit ecap_pwm_probe(struct platform_device *pdev)
>
> pc->chip.dev = &pdev->dev;
> pc->chip.ops = &ecap_pwm_ops;
> + pc->chip.of_pwm_n_cells = PWM_CELL_SIZE;
> pc->chip.base = -1;
> pc->chip.npwm = 1;
>
> @@ -231,14 +252,37 @@ static int __devinit ecap_pwm_probe(struct platform_device *pdev)
> }
>
> pm_runtime_enable(&pdev->dev);
> + pm_runtime_get_sync(&pdev->dev);
Maybe put a blank line after this for readability.
> + if (!(pwmss_submodule_state_change(pdev->dev.parent, ECAPCLK_EN) &
> + ECAPCLK_EN_ACK)) {
This is very hard to read, can you split this up into something like the
following please?
status = pwmss_submodule_state_change(pdev->dev.parent, ECAPCLK_EN);
if (!(status & ECAPCLK_EN_ACK)) {
...
}
> + dev_err(&pdev->dev, "PWMSS config space clock enable failure\n");
> + ret = -EINVAL;
> + goto pwmss_clk_failure;
> + }
> + pm_runtime_put_sync(&pdev->dev);
Another blank line between the two above would be good.
> +
> platform_set_drvdata(pdev, pc);
> return 0;
> +
> +pwmss_clk_failure:
> + pm_runtime_put_sync(&pdev->dev);
> + pm_runtime_disable(&pdev->dev);
> + pwmchip_remove(&pc->chip);
> + return ret;
> }
>
> static int __devexit ecap_pwm_remove(struct platform_device *pdev)
No __devexit please.
> {
> struct ecap_pwm_chip *pc = platform_get_drvdata(pdev);
>
> + pm_runtime_get_sync(&pdev->dev);
> + /*
> + * Due to hardware misbehaviour, acknowledge of the stop_req
> + * is missing. Hence checking of the status bit skipped.
> + */
> + pwmss_submodule_state_change(pdev->dev.parent, ECAPCLK_STOP_REQ);
> + pm_runtime_put_sync(&pdev->dev);
> +
> pm_runtime_put_sync(&pdev->dev);
> pm_runtime_disable(&pdev->dev);
> return pwmchip_remove(&pc->chip);
> @@ -246,7 +290,9 @@ static int __devexit ecap_pwm_remove(struct platform_device *pdev)
>
> static struct platform_driver ecap_pwm_driver = {
> .driver = {
> - .name = "ecap",
> + .name = "ecap",
> + .owner = THIS_MODULE,
> + .of_match_table = of_match_ptr(ecap_of_match),
Here as well, if AM33xx is DT-only, then the of_match_ptr() can be
dropped.
> },
> .probe = ecap_pwm_probe,
> .remove = __devexit_p(ecap_pwm_remove),
No __devexit_p() please.
Thierry
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