Subject: Re: [RFC 2/5] hwspinlock: Add Realtek RTD1195 SB2

From: Fabien DESSENNE <[email-masked]>
Date: Tue, 3 Dec 2019 08:46:17 +0000

Hi Andreas

Few comments below.

BR

Fabien

On 02/12/2019 11:05 PM, Andreas Färber wrote:
> Implement a driver for hardware semaphores found in RTD1195 SoC.
> It allows for both per-register instances (SB2_HD_SEM) as well as
> contiguous register ranges (SB2_HD_SEM_NEW[0-7]).
>
> While these registers are part of the SB2 syscon, this implementation
> does not use syscon, to allow assigning one as SB2 syscon's hwlock.
>
> Cc: Cheng-Yu Lee <[email-masked]>
> Signed-off-by: Andreas Färber <[email-masked]>
> ---
>   drivers/hwspinlock/Kconfig           |  11 ++++
>   drivers/hwspinlock/Makefile          |   1 +
>   drivers/hwspinlock/rtd1195_sb2_sem.c | 101 +++++++++++++++++++++++++++++++++++
>   3 files changed, 113 insertions(+)
>   create mode 100644 drivers/hwspinlock/rtd1195_sb2_sem.c
>
> diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
> index 37740e992cfa..9c26c436d399 100644
> --- a/drivers/hwspinlock/Kconfig
> +++ b/drivers/hwspinlock/Kconfig
> @@ -28,6 +28,17 @@ config HWSPINLOCK_QCOM
>   
>   	  If unsure, say N.
>   
> +config HWSPINLOCK_RTD1195_SB2
> +	tristate "Realtek RTD1195 SB2 Hardware Spinlock device"
> +	depends on HWSPINLOCK
> +	depends on ARCH_REALTEK || COMPILE_TEST
> +	default ARCH_REALTEK
> +	help
> +	  Say y here to support the Realtek Hardware Semaphore functionality,
> +	  found on the RTD1195 and later SoC families.
> +
> +	  If unsure, say N.
> +
>   config HWSPINLOCK_SIRF
>   	tristate "SIRF Hardware Spinlock device"
>   	depends on HWSPINLOCK
> diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
> index ed053e3f02be..d5bd59412468 100644
> --- a/drivers/hwspinlock/Makefile
> +++ b/drivers/hwspinlock/Makefile
> @@ -6,6 +6,7 @@
>   obj-$(CONFIG_HWSPINLOCK)		+= hwspinlock_core.o
>   obj-$(CONFIG_HWSPINLOCK_OMAP)		+= omap_hwspinlock.o
>   obj-$(CONFIG_HWSPINLOCK_QCOM)		+= qcom_hwspinlock.o
> +obj-$(CONFIG_HWSPINLOCK_RTD1195_SB2)	+= rtd1195_sb2_sem.o
>   obj-$(CONFIG_HWSPINLOCK_SIRF)		+= sirf_hwspinlock.o
>   obj-$(CONFIG_HWSPINLOCK_SPRD)		+= sprd_hwspinlock.o
>   obj-$(CONFIG_HWSPINLOCK_STM32)		+= stm32_hwspinlock.o
> diff --git a/drivers/hwspinlock/rtd1195_sb2_sem.c b/drivers/hwspinlock/rtd1195_sb2_sem.c
> new file mode 100644
> index 000000000000..ae925d057874
> --- /dev/null
> +++ b/drivers/hwspinlock/rtd1195_sb2_sem.c
> @@ -0,0 +1,101 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * RTD1195 SB2 hardware semaphore
> + *
> + * Copyright (c) 2019 Andreas Färber
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/hwspinlock.h>
> +#include <linux/idr.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +
> +#include "hwspinlock_internal.h"
> +
> +struct rtd1195_sb2_sem {
> +	struct platform_device *pdev;
> +	void __iomem *base;
> +	int base_id;
The pdev, base and base_id members of this struct are set in .probe() 
but never read anywhere: you may remove them and keep only lockdev
> +	struct hwspinlock_device lockdev;
> +};
> +
> +static DEFINE_IDR(rtd1195_sb2_sem_idr);
> +
> +static int rtd1195_sb2_sem_trylock(struct hwspinlock *lock)
> +{
> +	void __iomem *reg = (void __iomem *)lock->priv;
> +
> +	return readl_relaxed(reg) & BIT(0);
> +}
> +
> +static void rtd1195_sb2_sem_unlock(struct hwspinlock *lock)
> +{
> +	void __iomem *reg = (void __iomem *)lock->priv;
> +
> +	writel_relaxed(0, reg);
> +}
> +
> +static const struct hwspinlock_ops rtd1195_sb2_sem_hwspinlock_ops = {
> +	.trylock	= rtd1195_sb2_sem_trylock,
> +	.unlock		= rtd1195_sb2_sem_unlock,
> +};
> +
> +static int rtd1195_sb2_sem_probe(struct platform_device *pdev)
> +{
> +	struct rtd1195_sb2_sem *sem;
> +	struct hwspinlock *lock;
> +	struct resource *res;
> +	int i, num;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!res)
> +		return -ENOMEM;
> +
> +	num = resource_size(res) / 4;
> +
> +	sem = devm_kzalloc(&pdev->dev, sizeof(*sem) + num * sizeof(*lock),
> +			   GFP_KERNEL);
> +	if (!sem)
> +		return -ENOMEM;
> +
> +	sem->pdev = pdev;
> +
> +	sem->base = of_iomap(pdev->dev.of_node, 0);
You may use devm_ioremap_resource() here.
> +	if (!sem->base)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < num; i++) {
> +		lock = &sem->lockdev.lock[i];
> +		lock->priv = sem->base + i * 4;
> +	}
> +
> +	platform_set_drvdata(pdev, sem);
> +
> +	sem->base_id = idr_alloc(&rtd1195_sb2_sem_idr, sem, 0, 0, GFP_KERNEL);
> +
> +	return devm_hwspin_lock_register(&pdev->dev, &sem->lockdev,
> +		&rtd1195_sb2_sem_hwspinlock_ops, sem->base_id, num);
> +}
> +
> +static const struct of_device_id rtd1195_sb2_sem_dt_ids[] = {
> +	{ .compatible = "realtek,rtd1195-sb2-sem" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, rtd1195_sb2_sem_dt_ids);
> +
> +static struct platform_driver rtd1195_sb2_sem_platform_driver = {
> +	.driver = {
> +		.name = "rtd1195-sb2-sem",
> +		.of_match_table = rtd1195_sb2_sem_dt_ids,
> +	},
> +	.probe = rtd1195_sb2_sem_probe,
> +};
> +module_platform_driver(rtd1195_sb2_sem_platform_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Hardware spinlock driver for Realtek RTD1195 SB2");
> +MODULE_AUTHOR("Andreas Färber <[email-masked]>");
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