Re: [PATCH v6 2/2] hwspinlock: qcom: Add support for Qualcomm HW, Mutex block

[Tim Bird <tim.bird@sonymobile.com>]

My apologies for the dup.  gmail somehow added html to my original message and
it got rejected by multiple maillists.

> On Fri, Feb 27, 2015 at 2:30 PM, Bjorn Andersson <bjorn.andersson@sonymobile.com> wrote:
> 
> Add driver for Qualcomm Hardware Mutex block found in many Qualcomm
> SoCs.
> 
> Based on initial effort by Kumar Gala <galak@codeaurora.org>
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
> ---
> 
> As Andy Gross introduced the tcsr syscon we can no longer just ioremap the
> memory directly, so rework the driver to run ontop of syscon.
> 
> Changes since v5:
> - Dropped all but hwspinlock specific dt bindings
> - Hardcoded the number of locks (there is 32)
> - Rework to sit ontop of syscon
> 
> Changes since v4:
> - Aligned with devicetree support in hwlock framework and hence depends on [1]
> 
> Changes since v3:
> - Reverted back to getting stride from of_match, per Kumars request
> 
> Changes since v2:
> - MODULE_DEVICE_TABLE
> - Changed prefix to qcom
> - Cleaned up includes
> - Rely on reg and num-locks to figure out stride, instead of of_match data
> 
> Changes since v1:
> - Added the pm_runtime calls needed to be able to boot a kernel with
>   pm_runtime and this driver, patch from Courtney.
> - Added sfpb-mutex compatible, for re-use of the driver in family A platforms.
> - Updated formatting of DT binding documentation, while adding the extra
>   compatible.
> - Dropped Stephen Boyds Reviewed-by due to these changes.
> 
>  drivers/hwspinlock/Kconfig           |  11 +++
>  drivers/hwspinlock/Makefile          |   1 +
>  drivers/hwspinlock/qcom_hwspinlock.c | 181 +++++++++++++++++++++++++++++++++++
>  3 files changed, 193 insertions(+)
>  create mode 100644 drivers/hwspinlock/qcom_hwspinlock.c
> 
> diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
> index 3612cb5..762216d 100644
> --- a/drivers/hwspinlock/Kconfig
> +++ b/drivers/hwspinlock/Kconfig
> @@ -18,6 +18,17 @@ config HWSPINLOCK_OMAP
> 
>           If unsure, say N.
> 
> +config HWSPINLOCK_QCOM
> +       tristate "Qualcomm Hardware Spinlock device"
> +       depends on ARCH_QCOM
> +       select HWSPINLOCK
> +       help
> +         Say y here to support the Qualcomm Hardware Mutex functionality, which
> +         provides a synchronisation mechanism for the various processors on
> +         the SoC.
> +
> +         If unsure, say N.
> +
>  config HSEM_U8500
>         tristate "STE Hardware Semaphore functionality"
>         depends on ARCH_U8500
> diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
> index 93eb64b..68f95d9 100644
> --- a/drivers/hwspinlock/Makefile
> +++ b/drivers/hwspinlock/Makefile
> @@ -4,4 +4,5 @@
> 
>  obj-$(CONFIG_HWSPINLOCK)               += hwspinlock_core.o
>  obj-$(CONFIG_HWSPINLOCK_OMAP)          += omap_hwspinlock.o
> +obj-$(CONFIG_HWSPINLOCK_QCOM)          += qcom_hwspinlock.o
>  obj-$(CONFIG_HSEM_U8500)               += u8500_hsem.o
> diff --git a/drivers/hwspinlock/qcom_hwspinlock.c
> b/drivers/hwspinlock/qcom_hwspinlock.c
> new file mode 100644
> index 0000000..93b62e0
> --- /dev/null
> +++ b/drivers/hwspinlock/qcom_hwspinlock.c
> @@ -0,0 +1,181 @@
> +/*
> + * Copyright (c) 2013, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2015, Sony Mobile Communications AB
> + *
> + * 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/hwspinlock.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>
> +
> +#include "hwspinlock_internal.h"
> +
> +#define QCOM_MUTEX_APPS_PROC_ID        1
> +#define QCOM_MUTEX_NUM_LOCKS   32
> +
> +static int qcom_hwspinlock_trylock(struct hwspinlock *lock)
> +{
> +       struct regmap_field *field = lock->priv;
> +       u32 lock_owner;
> +       int ret;
> +
> +       ret = regmap_field_write(field, QCOM_MUTEX_APPS_PROC_ID);
> +       if (ret)
> +               return ret;
> +
> +       ret = regmap_field_read(field, &lock_owner);
> +       if (ret)
> +               return ret;
> +
> +       return lock_owner == QCOM_MUTEX_APPS_PROC_ID;
> +}
> +
> +static void qcom_hwspinlock_unlock(struct hwspinlock *lock)
> +{
> +       struct regmap_field *field = lock->priv;
> +       u32 lock_owner;
> +       int ret;
> +
> +       ret = regmap_field_read(field, &lock_owner);
> +       if (ret) {
> +               pr_err("%s: unable to query spinlock owner\n", __func__);
> +               return;
> +       }
> +
> +       if (lock_owner != QCOM_MUTEX_APPS_PROC_ID) {
> +               pr_err("%s: spinlock not owned by us (actual owner is %d)\n",
> +                               __func__, lock_owner);
> +       }
> +
> +       ret = regmap_field_write(field, 0);
> +       if (ret)
> +               pr_err("%s: failed to unlock spinlock\n", __func__);
> +}
> +
> +static const struct hwspinlock_ops qcom_hwspinlock_ops = {
> +       .trylock        = qcom_hwspinlock_trylock,
> +       .unlock         = qcom_hwspinlock_unlock,
> +};
> +
> +static const struct of_device_id qcom_hwspinlock_of_match[] = {
> +       { .compatible = "qcom,sfpb-mutex" },
> +       { .compatible = "qcom,tcsr-mutex" },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(of, qcom_hwspinlock_of_match);
> +
> +static int qcom_hwspinlock_probe(struct platform_device *pdev)
> +{
> +       struct hwspinlock_device *bank;
> +       struct device_node *syscon;
> +       struct reg_field field;
> +       struct regmap *regmap;
> +       size_t array_size;
> +       u32 stride;
> +       u32 base;
> +       int ret;
> +       int i;
> +
> +       syscon = of_parse_phandle(pdev->dev.of_node, "syscon", 0);
> +       if (!syscon) {
> +               dev_err(&pdev->dev, "no syscon property\n");
> +               return -ENODEV;
> +       }
> +
> +       regmap = syscon_node_to_regmap(syscon);
> +       if (IS_ERR(regmap))
> +               return PTR_ERR(regmap);
> +
> +       ret = of_property_read_u32_index(pdev->dev.of_node, "syscon", 1, &base);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "no offset in syscon\n");
> +               return -EINVAL;
> +       }
> +
> +       ret = of_property_read_u32_index(pdev->dev.of_node, "syscon",
> 2, &stride);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "no stride syscon\n");
> +               return -EINVAL;
> +       }
> +
> +       array_size = QCOM_MUTEX_NUM_LOCKS * sizeof(struct hwspinlock);
> +       bank = devm_kzalloc(&pdev->dev, sizeof(*bank) + array_size, GFP_KERNEL);
> +       if (!bank)
> +               return -ENOMEM;
> +
> +       platform_set_drvdata(pdev, bank);
> +
> +       for (i = 0; i < QCOM_MUTEX_NUM_LOCKS; i++) {
> +               field.reg = base + i * stride;
> +               field.lsb = 0;
> +               field.msb = 32;
> +
> +               bank->lock[i].priv = devm_regmap_field_alloc(&pdev->dev,
> +                                                            regmap, field);
> +       }
> +
> +       pm_runtime_enable(&pdev->dev);
> +
> +       ret = hwspin_lock_register(bank, &pdev->dev, &qcom_hwspinlock_ops,
> +                                  0, QCOM_MUTEX_NUM_LOCKS);
> +       if (ret)
> +               pm_runtime_disable(&pdev->dev);
> +
> +       return ret;
> +}
> +
> +static int qcom_hwspinlock_remove(struct platform_device *pdev)
> +{
> +       struct hwspinlock_device *bank = platform_get_drvdata(pdev);
> +       int ret;
> +
> +       ret = hwspin_lock_unregister(bank);
> +       if (ret) {
> +               dev_err(&pdev->dev, "%s failed: %d\n", __func__, ret);
> +               return ret;
> +       }
> +
> +       pm_runtime_disable(&pdev->dev);
> +
> +       return 0;
> +}
> +
> +static struct platform_driver qcom_hwspinlock_driver = {
> +       .probe          = qcom_hwspinlock_probe,
> +       .remove         = qcom_hwspinlock_remove,
> +       .driver         = {
> +               .name   = "qcom_hwspinlock",
> +               .of_match_table = qcom_hwspinlock_of_match,
> +       },
> +};
> +
> +static int __init qcom_hwspinlock_init(void)
> +{
> +       return platform_driver_register(&qcom_hwspinlock_driver);
> +}
> +/* board init code might need to reserve hwspinlocks for predefined purposes */
> +postcore_initcall(qcom_hwspinlock_init);
> +
> +static void __exit qcom_hwspinlock_exit(void)
> +{
> +       platform_driver_unregister(&qcom_hwspinlock_driver);
> +}
> +module_exit(qcom_hwspinlock_exit);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Hardware spinlock driver for Qualcomm SoCs");
> --
> 1.8.2.2

I'm pretty anxious about this one, as my current work has a dependency on it.
Virtually the entirety of the QualComm SOC work is dependent on this
because it's needed by the interprocessor communication framework
and the regulator driver.

I assume we're waiting on the response from Ohad about getting this upstream?
It's been almost 2 weeks with no reply.

Ohad - do you plan to do anything with this patch?  We seem to be at an impasse
(once again).

This is the 6th attempt over the course of the last year and a half to get
this hwspinlock code mainlined.  Should we just not use the hwspinlock
framework?

What are our options going forward?

 -- Tim Bird
Senior Software Engineer, Sony Mobile
Architecture Group Chair, CE Workgroup, Linux Foundation