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

[Stephen Boyd <sboyd@codeaurora.org>]

On 07/29, Kumar Gala wrote:
> > diff --git a/Documentation/devicetree/bindings/arm/msm/tcsr-mutex.txt b/Documentation/devicetree/bindings/arm/msm/tcsr-mutex.txt
> > new file mode 100644
> > index 0000000..ddd6889
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/arm/msm/tcsr-mutex.txt

Maybe this should go under a new hwspinlock directory?

> > @@ -0,0 +1,20 @@
> > +Qualcomm MSM Hardware Mutex Block:
> > +
> > +The hardware block provides mutexes utilized between different processors
> > +on the SoC as part of the communication protocol used by these processors.
> > +
> > +Required properties:
> > +- compatible: should be "qcom,tcsr-mutex"
> > +- reg: Should contain registers location and length of mutex registers
> > +- reg-names:
> > +	"mutex-base"  - string to identify mutex registers
> > +- qcom,num-locks: the number of locks/mutexes supported
> > +
> > +Example:
> > +
> > +	qcom,tcsr-mutex@fd484000 {

Maybe it should be hw-mutex@fd484000?

> > +		compatible = "qcom,tcsr-mutex";
> > +		reg = <0xfd484000 0x1000>;
> > +		reg-names = "mutex-base";
> > +		qcom,num-locks = <32>;
> > +	};
> > diff --git a/drivers/hwspinlock/msm_hwspinlock.c b/drivers/hwspinlock/msm_hwspinlock.c
> > new file mode 100644
> > index 0000000..c7d80c5
> > --- /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 <asm/io.h>

<linux/io.h> please.

> > +
> > +#include "hwspinlock_internal.h"
> > +
> > +#define SPINLOCK_ID_APPS_PROC	1
> > +#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();

Are you sure you don't want mb() instead? What is this barrier
for? Comment please.

> > +	return readl_relaxed(lock_addr) == SPINLOCK_ID_APPS_PROC;
> > +}
> > +
> > +static void msm_hwspinlock_unlock(struct hwspinlock *lock)
> > +{
> > +	int lock_owner;
> > +	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",
> > +				__func__, lock_owner);
> > +	}
> > +
> > +	writel_relaxed(0, lock_addr);
> > +	smp_mb();

Same here. What is smp_mb() for?

> > +}
> > +
> > +static const struct hwspinlock_ops msm_hwspinlock_ops = {
> > +	.trylock	= msm_hwspinlock_trylock,
> > +	.unlock		= msm_hwspinlock_unlock,
> > +};
> > +
> > +static struct of_device_id msm_hwspinlock_of_match[];

Why not just put the match table here then? Also, can it be
const?

> > +static int msm_hwspinlock_probe(struct platform_device *pdev)
> > +{
> > +	int ret, i, stride;
> > +	u32 num_locks;
> > +	struct hwspinlock_device *bank;
> > +	struct hwspinlock *hwlock;
> > +	struct resource *res;
> > +	void __iomem *iobase;
> > +	struct device_node *node = pdev->dev.of_node;
> > +	const struct of_device_id *match;
> > +
> > +	match = of_match_device(msm_hwspinlock_of_match, &pdev->dev);
> > +	if (!match)
> > +		return -EINVAL;
> > +
> > +	ret = of_property_read_u32(node, "qcom,num-locks", &num_locks);
> > +	if (ret || (num_locks == 0))

Drop useless ().

> > +		return -ENODEV;
> > +
> > +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mutex-base");
> > +	iobase = devm_ioremap_resource(&pdev->dev, res);
> > +	if (IS_ERR(iobase))
> > +		return PTR_ERR(iobase);
> > +
> > +	bank = devm_kzalloc(&pdev->dev,
> > +		 sizeof(*bank) + num_locks * sizeof(*hwlock), GFP_KERNEL);
> > +	if (!bank)
> > +		return -ENOMEM;
> > +

Style Nit: Maybe we could grow a local variable to get this to be
one line.

	size_t array_size;

	array_size = num_lock * sizeof(*hwlock);
	bank = devm_kzalloc(&pdev->dev, sizeof(*bank) + array_size, GFP_KERNEL);

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