linux-kernel - Re: [PATCH v2] hwspinlock/msm: Add support for Qualcomm MSM HW Mutex block

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Date:	Mon, 12 Aug 2013 09:35:53 -0700
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Kumar Gala <galak@...eaurora.org>
CC:	ohad@...ery.com, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
	Jeffrey Hugo <jhugo@...eaurora.org>,
	Eric Holmberg <eholmber@...eaurora.org>
Subject: Re: [PATCH v2] hwspinlock/msm: Add support for Qualcomm MSM HW Mutex
 block

On 07/29/13 15:00, Kumar Gala wrote:
> diff --git a/drivers/hwspinlock/msm_hwspinlock.c b/drivers/hwspinlock/msm_hwspinlock.c
> new file mode 100644
> index 0000000..dbd9a69
> --- /dev/null
> +++ b/drivers/hwspinlock/msm_hwspinlock.c
> @@ -0,0 +1,150 @@
> +/*
> + * Copyright (c) 2013, The Linux Foundation. All rights reserved.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/device.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/hwspinlock.h>
> +#include <linux/io.h>
> +
> +#include "hwspinlock_internal.h"
> +
> +#define SPINLOCK_ID_APPS_PROC	1

Is this id only for the apps processor? What about hexagon? Does it need
a different number?

> +#define BASE_ID			0
> +
> +static int msm_hwspinlock_trylock(struct hwspinlock *lock)
> +{
> +	void __iomem *lock_addr = lock->priv;
> +
> +	writel_relaxed(SPINLOCK_ID_APPS_PROC, lock_addr);
> +	smp_mb();
> +	return readl_relaxed(lock_addr) == SPINLOCK_ID_APPS_PROC;
> +}
> +
> +static void msm_hwspinlock_unlock(struct hwspinlock *lock)
> +{
> +	int lock_owner;

This should probably be u32 to be explicit about the size of the register.

> +	void __iomem *lock_addr = lock->priv;
> +
> +	lock_owner = readl_relaxed(lock_addr);
> +	if (lock_owner != SPINLOCK_ID_APPS_PROC) {
> +		pr_err("%s: spinlock not owned by Apps (actual owner is %d)\n",

Maybe you should just say "spinlock not owned by us (actual owner is
%d)" so that this driver is agnostic to the processor it runs on?

> +				__func__, lock_owner);
> +	}
> +
> +	writel_relaxed(0, lock_addr);
> +	smp_mb();
> +}
>

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation

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