Re: [PATCH 10/11] clocksource: flexcard: Add basic timestamp counter support

[Daniel Lezcano <daniel.lezcano@linaro.org>]

Hi Holger,

[Cc'ed John Stultz]

On 03/25/2015 10:51 AM, Holger Dengler wrote:
> From: Benedikt Spranger <b.spranger@linutronix.de>
>
> The Eberspaecher Flexcard PMC II offers a Flexray network synchronized
> counter with a selectable resolution of 1us, 100ns or 10ns. Add basic
> support for the timestamp counter with 1us resolution, which is the
> standard Flexray bus resolution.
>
> Signed-off-by: Holger Dengler <dengler@linutronix.de>
> Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
> cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> cc: Thomas Gleixner <tglx@linutronix.de>
> ---
>   drivers/clocksource/Kconfig         |  11 ++
>   drivers/clocksource/Makefile        |   1 +
>   drivers/clocksource/flexcard-time.c | 235 ++++++++++++++++++++++++++++++++++++
>   include/linux/mfd/flexcard.h        |   6 +
>   4 files changed, 253 insertions(+)
>   create mode 100644 drivers/clocksource/flexcard-time.c
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 68161f7..a6b9308 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -250,4 +250,15 @@ config CLKSRC_PXA
>   	help
>   	  This enables OST0 support available on PXA and SA-11x0
>   	  platforms.
> +
> +config CLKSRC_FLEXCARD
> +	tristate "Support for Flexcard clock function"

Why do you need this to be a module ?

The Kconfig policy is to have it selected by the arch Kconfig.

It should be like:

config CLKSRC_FLEXCARD
	bool
	select CLKSRC_MMIO

and then the Kconfig for MFD_FLEXCARD selects CLKSRC_FLEXCARD.

> +	depends on MFD_FLEXCARD
> +	select CLKSRC_MMIO
> +	help
> +	  This is the clocksource function driver for the
> +	  Eberspaecher Flexcard PMC II carrier board. The
> +	  Flexcard provide a Flexray synchronized counter
> +	  configurable at 1, 10 or 100MHz.
> +
>   endmenu
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 752d5c7..8bbc657 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -51,3 +51,4 @@ obj-$(CONFIG_ARCH_INTEGRATOR_AP)	+= timer-integrator-ap.o
>   obj-$(CONFIG_CLKSRC_VERSATILE)		+= versatile.o
>   obj-$(CONFIG_CLKSRC_MIPS_GIC)		+= mips-gic-timer.o
>   obj-$(CONFIG_ASM9260_TIMER)		+= asm9260_timer.o
> +obj-$(CONFIG_CLKSRC_FLEXCARD)		+= flexcard-time.o
> diff --git a/drivers/clocksource/flexcard-time.c b/drivers/clocksource/flexcard-time.c
> new file mode 100644
> index 0000000..f2efb53
> --- /dev/null
> +++ b/drivers/clocksource/flexcard-time.c
> @@ -0,0 +1,235 @@
> +/*
> + * Eberspaecher Flexcard PMC II - clocksource driver
> + *
> + * Copyright (c) 2014,2015 Linutronix GmbH
> + * Author: Holger Dengler
> + *         Benedikt Spranger
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> + * by the Free Software Foundation.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/fs.h>
> +#include <linux/miscdevice.h>
> +#include <linux/platform_device.h>
> +#include <linux/posix-clock.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/flexcard.h>
> +
> +#define MAX_CLOCKS   16
> +#define CLKSEL_OFF   0x10
> +
> +static dev_t flexcard_clk_devt;
> +static struct class *flexcard_clk_class;
> +
> +struct flexcard_clk {
> +	struct posix_clock clock;
> +	dev_t devid;
> +	struct device *dev;
> +	void __iomem *ts64;
> +	void __iomem *reset;
> +};
> +
> +static int flexcard_clk_getres(struct posix_clock *pc, struct timespec *tp)
> +{
> +	tp->tv_sec = 0;
> +	tp->tv_nsec = 1000;
> +
> +	return 0;
> +}
> +
> +static int flexcard_clk_gettime(struct posix_clock *pc, struct timespec *tp)
> +{
> +	struct flexcard_clk *clk = container_of(pc, struct flexcard_clk, clock);
> +	u64 now;
> +	u32 upper, rem;
> +
> +retry:
> +	upper = readl(clk->ts64);
> +	now = ((u64) upper << 32) | readl(clk->ts64 + 4);
> +	if (upper != readl(clk->ts64))
> +		goto retry;
> +
> +	tp->tv_sec = div_u64_rem(now, clk->desc.freq, &rem);
> +	tp->tv_nsec = rem * 1000;
> +
> +	return 0;
> +}
> +
> +static int flexcard_clk_settime(struct posix_clock *pc,
> +				const struct timespec *tp)
> +{
> +	struct flexcard_clk *clk = container_of(pc, struct flexcard_clk, clock);
> +
> +	/* The FlexCard clock could only be reset to 0 and not set */
> +	if (tp->tv_sec || tp->tv_nsec)
> +		return -EINVAL;
> +
> +	writel(FLEXCARD_RST_TS, clk->reset);
> +
> +	return 0;
> +}
> +
> +static struct posix_clock_operations flexcard_clk_ops = {
> +	.owner		= THIS_MODULE,
> +	.clock_getres	= flexcard_clk_getres,
> +	.clock_gettime	= flexcard_clk_gettime,
> +	.clock_settime	= flexcard_clk_settime,
> +};
> +
> +static int flexcard_clksrc_iomap(struct platform_device *pdev)
> +{
> +	struct flexcard_clk *clk = platform_get_drvdata(pdev);
> +	struct resource *res;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENXIO;
> +
> +	clk->ts64 = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (!clk->ts64)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	if (!res)
> +		return -ENXIO;
> +
> +	clk->reset = devm_ioremap(&pdev->dev, res->start, resource_size(res));
> +	if (!clk->reset)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static int flexcard_clksrc_probe(struct platform_device *pdev)
> +{
> +	const struct mfd_cell *cell;
> +	struct flexcard_clk *clk;
> +	int major, ret;
> +
> +	cell = mfd_get_cell(pdev);
> +	if (!cell)
> +		return -ENODEV;
> +
> +	if (cell->id >= MAX_CLOCKS) {
> +		dev_err(&pdev->dev, "all flexcard posix clocks in use\n");
> +		return -EBUSY;
> +	}
> +
> +	clk = devm_kzalloc(&pdev->dev, sizeof(*clk), GFP_KERNEL);
> +	if (!clk)
> +		return -ENOMEM;
> +
> +	major = MAJOR(flexcard_clk_devt);
> +	platform_set_drvdata(pdev, clk);
> +
> +	ret = flexcard_clksrc_iomap(pdev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to map resources: %d\n", ret);
> +		goto out;
> +	}
> +
> +	clk->devid = MKDEV(major, cell->id);
> +	clk->clock.ops = flexcard_clk_ops;
> +
> +	writel(FLEXCARD_CLK_1MHZ, clk->ts64 + CLKSEL_OFF);
> +	writel(FLEXCARD_RST_TS, clk->reset);
> +
> +	clk->dev = device_create(flexcard_clk_class, &pdev->dev, clk->devid,
> +				 clk, "flexcard_clk%d", cell->id);
> +	if (IS_ERR(clk->dev)) {
> +		ret = PTR_ERR(clk->dev);
> +		goto out;
> +	}
> +
> +	ret = posix_clock_register(&clk->clock, clk->devid);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"failed to register flexcard posix clock: %d\n", ret);
> +		goto out_destroy;
> +	}
> +
> +	dev_info(&pdev->dev, "flexcard posix clock %d registered", cell->id);
> +
> +	return 0;
> +
> +out_destroy:
> +	device_destroy(flexcard_clk_class, clk->devid);
> +out:
> +	return ret;
> +}
> +
> +static int flexcard_clksrc_remove(struct platform_device *pdev)
> +{
> +	struct flexcard_clk *clk = platform_get_drvdata(pdev);
> +
> +	posix_clock_unregister(&clk->clock);
> +	device_destroy(flexcard_clk_class, clk->devid);
> +	platform_set_drvdata(pdev, NULL);
> +
> +	return 0;
> +}
> +
> +static const struct platform_device_id flexcard_clksrc_id_table[] = {
> +	{ "flexcard-clksrc", 0 },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(platform, flexcard_clksrc_id_table);
> +
> +static struct platform_driver flexcard_clksrc_driver = {
> +	.probe		= flexcard_clksrc_probe,
> +	.remove		= flexcard_clksrc_remove,
> +	.driver		= {
> +		.name	= "flexcard-clksrc",
> +	},
> +	.id_table	= flexcard_clksrc_id_table,
> +};
> +
> +static int __init flexcard_clksrc_init(void)
> +{
> +	int ret;
> +
> +	flexcard_clk_class = class_create(THIS_MODULE, "flexcard_clk");
> +	if (IS_ERR(flexcard_clk_class)) {
> +		pr_err("flexcard_clk: failed to allocate class\n");
> +		return PTR_ERR(flexcard_clk_class);
> +	}
> +
> +	ret = alloc_chrdev_region(&flexcard_clk_devt, 0, MAX_CLOCKS,
> +				  "flexcard_clk");
> +	if (ret < 0) {
> +		pr_err("failed to allocate device region\n");
> +		goto out;
> +	}
> +
> +	ret = platform_driver_register(&flexcard_clksrc_driver);
> +	if (ret < 0)
> +		goto out_unregister;
> +
> +	return 0;
> +
> +out_unregister:
> +	unregister_chrdev_region(flexcard_clk_devt, MAX_CLOCKS);
> +out:
> +	class_destroy(flexcard_clk_class);
> +
> +	return ret;
> +}
> +
> +static void __exit flexcard_clksrc_exit(void)
> +{
> +	platform_driver_unregister(&flexcard_clksrc_driver);
> +	unregister_chrdev_region(flexcard_clk_devt, MAX_CLOCKS);
> +	class_destroy(flexcard_clk_class);
> +}
> +
> +MODULE_AUTHOR("Holger Dengler <dengler@linutronix.de>");
> +MODULE_AUTHOR("Benedikt Spranger <b.spranger@linutronix.de>");
> +MODULE_DESCRIPTION("Eberspaecher Flexcard PMC II clocksource driver");
> +MODULE_LICENSE("GPL v2");
> +
> +module_init(flexcard_clksrc_init);
> +module_exit(flexcard_clksrc_exit);
> diff --git a/include/linux/mfd/flexcard.h b/include/linux/mfd/flexcard.h
> index 964d78c..d7ecf3d 100644
> --- a/include/linux/mfd/flexcard.h
> +++ b/include/linux/mfd/flexcard.h
> @@ -19,8 +19,14 @@
>   #define FLEXCARD_FR_OFFSET	0x4000
>   #define FLEXCARD_FR_SIZE	0x2000
>
> +#define FLEXCARD_RST_TS		0x8000
> +
>   #define FLEXCARD_MAX_NAME	16
>
> +#define FLEXCARD_CLK_1MHZ	0
> +#define FLEXCARD_CLK_10MHZ	1
> +#define FLEXCARD_CLK_100MHZ	2
> +
>   struct flexcard_device {
>   	raw_spinlock_t irq_lock;
>   	struct pci_dev *pdev;
>


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