Messages in this thread |  | | Date | Sat, 21 Nov 2020 23:19:00 -0600 | From | Bjorn Andersson <> | Subject | Re: [PATCH 2/2] hwspinlock: add sunxi hardware spinlock support |
| |
On Wed 18 Nov 04:02 CST 2020, Wilken Gottwalt wrote:
> Adds the sunxi_hwspinlock driver and updates makefiles/maintainers. > > Signed-off-by: Wilken Gottwalt <wilken.gottwalt@posteo.net> > --- > MAINTAINERS | 6 + > drivers/hwspinlock/Kconfig | 9 + > drivers/hwspinlock/Makefile | 1 + > drivers/hwspinlock/sunxi_hwspinlock.c | 282 ++++++++++++++++++++++++++ > 4 files changed, 298 insertions(+) > create mode 100644 drivers/hwspinlock/sunxi_hwspinlock.c > > diff --git a/MAINTAINERS b/MAINTAINERS > index 5cc595ac7b28..7765da172f10 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -722,6 +722,12 @@ L: linux-crypto@vger.kernel.org > S: Maintained > F: drivers/crypto/allwinner/ > > +ALLWINNER HARDWARE SPINLOCK SUPPORT > +M: Wilken Gottwalt <wilken.gottwalt@posteo.net> > +S: Maintained > +F: Documentation/devicetree/bindings/hwlock/sunxi-hwspinlock.yaml > +F: drivers/hwspinlock/sunxi_hwspinlock.c > + > ALLWINNER THERMAL DRIVER > M: Vasily Khoruzhick <anarsoul@gmail.com> > M: Yangtao Li <tiny.windzz@gmail.com> > diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig > index 32cd26352f38..27b6e22126f7 100644 > --- a/drivers/hwspinlock/Kconfig > +++ b/drivers/hwspinlock/Kconfig > @@ -55,6 +55,15 @@ config HWSPINLOCK_STM32 > > If unsure, say N. > > +config HWSPINLOCK_SUNXI > + tristate "SUNXI Hardware Spinlock device" > + depends on ARCH_SUNXI || COMPILE_TEST > + help > + Say y here to support the Allwinner hardware mutex device available > + in the H2+, H3, H5 and H6 SoCs. > + > + If unsure, say N. > + > config HSEM_U8500 > tristate "STE Hardware Semaphore functionality" > depends on ARCH_U8500 || COMPILE_TEST > diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile > index ed053e3f02be..bf46bee95226 100644 > --- a/drivers/hwspinlock/Makefile > +++ b/drivers/hwspinlock/Makefile > @@ -9,4 +9,5 @@ obj-$(CONFIG_HWSPINLOCK_QCOM) += qcom_hwspinlock.o > obj-$(CONFIG_HWSPINLOCK_SIRF) += sirf_hwspinlock.o > obj-$(CONFIG_HWSPINLOCK_SPRD) += sprd_hwspinlock.o > obj-$(CONFIG_HWSPINLOCK_STM32) += stm32_hwspinlock.o > +obj-$(CONFIG_HWSPINLOCK_SUNXI) += sunxi_hwspinlock.o > obj-$(CONFIG_HSEM_U8500) += u8500_hsem.o > diff --git a/drivers/hwspinlock/sunxi_hwspinlock.c b/drivers/hwspinlock/sunxi_hwspinlock.c > new file mode 100644 > index 000000000000..54e6ad3ac1c2 > --- /dev/null > +++ b/drivers/hwspinlock/sunxi_hwspinlock.c > @@ -0,0 +1,282 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * sunxi_hwspinlock.c - hardware spinlock driver for Allwinner SoCs > + * Copyright (C) 2020 Wilken Gottwalt <wilken.gottwalt@posteo.net> > + */ > + > +#include <linux/bitops.h> > +#include <linux/clk.h> > +#include <linux/debugfs.h> > +#include <linux/errno.h> > +#include <linux/hwspinlock.h> > +#include <linux/io.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/reset.h> > +#include <linux/slab.h> > +#include <linux/spinlock.h> > +#include <linux/types.h> > + > +#include "hwspinlock_internal.h" > + > +#define DRIVER_NAME "sunxi_hwspinlock" > + > +#define SPINLOCK_BASE_ID 0 /* there is only one hwspinlock device in each SoC */ > +#define SPINLOCK_SYSSTATUS_REG 0x0000 > +#define SPINLOCK_STATUS_REG 0x0010 > +#define SPINLOCK_LOCK_REGN 0x0100 > +#define SPINLOCK_NOTTAKEN 0 > +#define SPINLOCK_TAKEN 1 > + > +struct sunxi_hwspinlock { > + void __iomem *io_base; > +}; > + > +struct sunxi_hwspinlock_data { > + void __iomem *io_base; > + struct hwspinlock_device *bank; > + struct reset_control *reset; > + struct clk *ahb_clock; > + struct dentry *debugfs; > + int nlocks; > +}; > + > +#ifdef CONFIG_DEBUG_FS > + > +static int hwlocks_supported_show(struct seq_file *seqf, void *unused) > +{ > + struct sunxi_hwspinlock_data *priv = seqf->private; > + > + seq_printf(seqf, "%d\n", priv->nlocks); > + > + return 0; > +} > +DEFINE_SHOW_ATTRIBUTE(hwlocks_supported); > + > +static int hwlocks_inuse_show(struct seq_file *seqf, void *unused) > +{ > + struct sunxi_hwspinlock_data *priv = seqf->private; > + int inuse; > + > + /* getting the status of only the main 32 spinlocks is supported */ > + inuse = hweight32(readl(priv->io_base + SPINLOCK_STATUS_REG));
So this returns how many of the locks are taken? How is that useful?
> + seq_printf(seqf, "%d\n", inuse); > + > + return 0; > +} > +DEFINE_SHOW_ATTRIBUTE(hwlocks_inuse); > + > +static void sunxi_hwspinlock_debugfs_init(struct sunxi_hwspinlock_data *priv) > +{ > + char name[32]; > + > + scnprintf(name, sizeof(name), "%s", DRIVER_NAME);
Why not just pass DRIVER_NAME directly to debugfs_create_dir()?
> + > + priv->debugfs = debugfs_create_dir(name, NULL); > + debugfs_create_file("hwlocks_supported", 0444, priv->debugfs, priv, > + &hwlocks_supported_fops); > + debugfs_create_file("hwlocks_inuse", 0444, priv->debugfs, priv, &hwlocks_inuse_fops); > +} > + > +#else > + > +static void sunxi_hwspinlock_debugfs_init(struct sunxi_hwspinlock_data *priv) > +{ > +} > + > +#endif > + > +static int sunxi_hwspinlock_trylock(struct hwspinlock *lock) > +{ > + struct sunxi_hwspinlock_data *priv = lock->priv; > + void __iomem *lock_addr = priv->io_base; > + > + return (readl(lock_addr) == SPINLOCK_NOTTAKEN); > +} > + > +static void sunxi_hwspinlock_unlock(struct hwspinlock *lock) > +{ > + struct sunxi_hwspinlock_data *priv = lock->priv; > + void __iomem *lock_addr = priv->io_base; > + > + writel(SPINLOCK_NOTTAKEN, lock_addr); > +} > + > +static const struct hwspinlock_ops sunxi_hwspinlock_ops = { > + .trylock = sunxi_hwspinlock_trylock, > + .unlock = sunxi_hwspinlock_unlock, > +}; > + > +static int sunxi_hwspinlock_probe(struct platform_device *pdev) > +{ > + struct device_node *node = pdev->dev.of_node;
I don't see a need for this, or the check to fail if it's NULL. Please remove it.
> + struct sunxi_hwspinlock_data *priv; > + struct sunxi_hwspinlock *hwpriv; > + struct hwspinlock *hwlock; > + struct resource *res; > + int num_banks, err, i; > + > + if (!node) > + return -ENODEV; > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + if (!res) > + return -ENODEV; > + > + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); > + if (!priv) > + return -ENOMEM; > + > + priv->io_base = devm_ioremap_resource(&pdev->dev, res);
Please use devm_platform_ioremap_resource() instead.
> + if (IS_ERR(priv->io_base)) { > + err = PTR_ERR(priv->io_base); > + dev_err(&pdev->dev, "unable to request MMIO (%d)\n", err); > + return err; > + } > + > + priv->ahb_clock = devm_clk_get(&pdev->dev, "ahb"); > + if (IS_ERR(priv->ahb_clock)) { > + err = PTR_ERR(priv->ahb_clock); > + dev_err(&pdev->dev, "unable to get AHB clock (%d)\n", err); > + return err; > + } > + > + priv->reset = devm_reset_control_get_optional(&pdev->dev, "ahb"); > + if (IS_ERR(priv->reset)) { > + err = PTR_ERR(priv->reset); > + if (err == -EPROBE_DEFER) > + return err; > + > + dev_info(&pdev->dev, "no optional reset control available (%d)\n", err);
In the even that no "ahb" reset is specified priv->reset is NULL, as such if you get here there's something wrong - so it's better to fail here.
And you can use the convenient dev_err_probe() function to deal with the EPROBE_DEFER.
> + priv->reset = NULL; > + } > + > + if (priv->reset) {
It's perfectly fine to call reset_control_deassert(NULL); so you can omit this check.
> + err = reset_control_deassert(priv->reset); > + if (err) { > + dev_err(&pdev->dev, "deassert reset control failure (%d)\n", err); > + return err; > + } > + } > + > + err = clk_prepare_enable(priv->ahb_clock); > + if (err) { > + dev_err(&pdev->dev, "unable to prepare AHB clock (%d)\n", err); > + goto reset_fail; > + } > + > + /* bit 28 and 29 hold the amount of spinlock banks */ > + num_banks = (readl(priv->io_base + SPINLOCK_SYSSTATUS_REG) >> 28) & 0x03; > + switch (num_banks) { > + case 1 ... 4:
But the comment above says...and num_banks was & 0x3, so how can it be ...4?
> + /* > + * 32, 64, 128 and 256 spinlocks are supported by the hardware implementation, > + * though most only support 32 spinlocks > + */ > + priv->nlocks = 1 << (4 + num_banks); > + break; > + default:
Given the mask above I believe this would only happen if bits 28 and 29 are both 0...
Regardless I think that this would be better written as a
if (num_banks == invalid) { ... goto fail; }
priv->nlocks = ...;
> + dev_err(&pdev->dev, "unsupported hwspinlock setup (%d)\n", num_banks); > + err = -EINVAL; > + goto fail; > + } > + > + /* > + * the Allwinner hwspinlock device uses 32bit registers for representing every single > + * spinlock, which is a real waste of space > + */
Might be a waste, but having them be the natural write size in hardware makes sense. I'm however not sure what this comment has to do with the following allocation.
> + priv->bank = devm_kzalloc(&pdev->dev, priv->nlocks * sizeof(*hwlock) + sizeof(*priv->bank),
Consider using struct_size() here.
> + GFP_KERNEL); > + if (!priv->bank) { > + err = -ENOMEM; > + goto fail;
If you do this allocation before you start the clock and deassert the reset you can just return -ENOMEM here, instead of the goto.
> + } > + > + for (i = 0, hwlock = &priv->bank->lock[0]; i < priv->nlocks; ++i, ++hwlock) { > + hwlock->priv = devm_kzalloc(&pdev->dev, sizeof(struct sunxi_hwspinlock), > + GFP_KERNEL);
hwpriv = devm_kzalloc(&pdev->dev, sizeof(*hwpriv), GFP_KERNEL); if (!hwpriv) return -ENOMEM;
hwpriv->io_base = ...; priv->bank->lock[i].priv = hwpriv;
> + if (!hwlock->priv) { > + err = -ENOMEM; > + goto fail; > + } > + > + hwpriv = hwlock->priv; > + hwpriv->io_base = priv->io_base + SPINLOCK_LOCK_REGN + sizeof(u32) * i; > + } > + > + err = hwspin_lock_register(priv->bank, &pdev->dev, &sunxi_hwspinlock_ops, SPINLOCK_BASE_ID, > + priv->nlocks); > + if (err) { > + dev_err(&pdev->dev, "unable to register hwspinlocks (%d)\n", err); > + goto fail; > + } > + > + sunxi_hwspinlock_debugfs_init(priv); > + > + dev_dbg(&pdev->dev, "SUNXI hardware spinlock driver enabled (%d locks)\n", priv->nlocks); > + > + return 0; > + > +fail: > + clk_disable_unprepare(priv->ahb_clock); > + > +reset_fail: > + if (priv->reset) > + reset_control_assert(priv->reset); > + > + return err; > +} > + > +static int sunxi_hwspinlock_remove(struct platform_device *pdev) > +{ > + struct sunxi_hwspinlock_data *priv = platform_get_drvdata(pdev); > + int err; > + > + debugfs_remove_recursive(priv->debugfs); > + > + err = hwspin_lock_unregister(priv->bank); > + if (err) { > + dev_err(&pdev->dev, "unregister device failed (%d)\n", err); > + return err; > + } > + > + if (priv->reset) > + reset_control_assert(priv->reset); > + > + clk_disable_unprepare(priv->ahb_clock);
By using devm_add_action_or_reset() to set up an "assert and unprepare"- function you can use devm_hwspin_lock_register(), you can drop the remove function and you can clean up your sunxi_hwspinlock_data (e.g. you no longer need a pointer to priv->bank).
> + > + return 0; > +} > + > +static const struct of_device_id sunxi_hwspinlock_ids[] = { > + { .compatible = "allwinner,sun8i-hwspinlock", }, > + { .compatible = "allwinner,sun50i-hwspinlock", }, > + {}, > +}; > +MODULE_DEVICE_TABLE(of, sunxi_hwspinlock_ids); > + > +static struct platform_driver sunxi_hwspinlock_driver = { > + .probe = sunxi_hwspinlock_probe, > + .remove = sunxi_hwspinlock_remove, > + .driver = { > + .name = DRIVER_NAME, > + .of_match_table = of_match_ptr(sunxi_hwspinlock_ids),
Please avoid of_match_ptr, as this will cause warnings about unused variables when COMPILE_TEST without OF.
Regards, Bjorn
> + }, > +}; > + > +static int __init sunxi_hwspinlock_init(void) > +{ > + return platform_driver_register(&sunxi_hwspinlock_driver); > +} > +postcore_initcall(sunxi_hwspinlock_init); > + > +static void __exit sunxi_hwspinlock_exit(void) > +{ > + platform_driver_unregister(&sunxi_hwspinlock_driver); > +} > +module_exit(sunxi_hwspinlock_exit); > + > +MODULE_LICENSE("GPL"); > +MODULE_DESCRIPTION("SUNXI hardware spinlock driver"); > +MODULE_AUTHOR("Wilken Gottwalt <wilken.gottwalt@posteo.net>"); > -- > 2.29.2 >
|  |