Messages in this thread | | | From | Samuel Holland <> | Subject | Re: [PATCH v4 2/2] hwspinlock: add sun8i hardware spinlock support | Date | Fri, 11 Dec 2020 08:40:50 -0600 |
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On 12/11/20 3:03 AM, Maxime Ripard wrote: > Hi, > > On Fri, Dec 11, 2020 at 09:24:15AM +0100, Wilken Gottwalt wrote: >> Adds the sun8i_hwspinlock driver for the hardware spinlock unit found in >> most of the sun8i compatible SoCs. >> >> This unit provides at least 32 spinlocks in hardware. The implementation >> supports 32, 64, 128 or 256 32bit registers. A lock can be taken by >> reading a register and released by writing a 0 to it. This driver >> supports all 4 spinlock setups, but for now only the first setup (32 >> locks) seem to exist in available devices. This spinlock unit is shared >> between all ARM cores and the embedded OpenRisc AR100 core. All of them >> can take/release a lock with a single cycle operation. It can be used to >> sync access to devices shared by the ARM cores and the OpenRisc core. >> >> There are two ways to check if a lock is taken. The first way is to read >> a lock. If a 0 is returned, the lock was free and is taken now. If an 1 >> is returned, the caller has to try again. Which means the lock is taken. >> The second way is to read a 32bit wide status register where every bit >> represents one of the 32 first locks. According to the datasheets this >> status register supports only the 32 first locks. This is the reason the >> first way (lock read/write) approach is used to be able to cover all 256 >> locks in future devices. The driver also reports the amount of supported >> locks via debugfs. >> >> Signed-off-by: Wilken Gottwalt <wilken.gottwalt@posteo.net> >> --- >> Changes in v4: >> - further simplified driver >> - fixed an add_action_and_reset_ function issue >> - changed bindings from sun8i-hwspinlock to sun8i-a33-hwspinlock >> >> Changes in v3: >> - moved test description to cover letter >> - changed name and symbols from sunxi to sun8i >> - improved driver description >> - further simplified driver >> - fully switched to devm_* and devm_add_action_* functions >> >> Changes in v2: >> - added suggestions from Bjorn Andersson and Maxime Ripard >> - provided better driver and test description >> --- >> MAINTAINERS | 6 + >> drivers/hwspinlock/Kconfig | 9 ++ >> drivers/hwspinlock/Makefile | 1 + >> drivers/hwspinlock/sun8i_hwspinlock.c | 197 ++++++++++++++++++++++++++ >> 4 files changed, 213 insertions(+) >> create mode 100644 drivers/hwspinlock/sun8i_hwspinlock.c >> >> diff --git a/MAINTAINERS b/MAINTAINERS >> index ebe4829cdd4d..46846113f1eb 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/sun8i-hwspinlock.yaml >> +F: drivers/hwspinlock/sun8i_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..b03fd99aab32 100644 >> --- a/drivers/hwspinlock/Kconfig >> +++ b/drivers/hwspinlock/Kconfig >> @@ -55,6 +55,15 @@ config HWSPINLOCK_STM32 >> >> If unsure, say N. >> >> +config HWSPINLOCK_SUN8I >> + tristate "SUN8I Hardware Spinlock device" >> + depends on ARCH_SUNXI || COMPILE_TEST >> + help >> + Say y here to support the SUN8I Hardware Spinlock device which can be >> + found in most of the sun8i compatible Allwinner 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..3496648d9257 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-$(CONFIG_HWSPINLOCK_SUN8I) += sun8i_hwspinlock.o >> obj-$(CONFIG_HSEM_U8500) += u8500_hsem.o >> diff --git a/drivers/hwspinlock/sun8i_hwspinlock.c b/drivers/hwspinlock/sun8i_hwspinlock.c >> new file mode 100644 >> index 000000000000..878dae6f1763 >> --- /dev/null >> +++ b/drivers/hwspinlock/sun8i_hwspinlock.c >> @@ -0,0 +1,197 @@ >> +// SPDX-License-Identifier: GPL-2.0-or-later >> +/* >> + * sun8i_hwspinlock.c - hardware spinlock driver for sun8i compatible Allwinner SoCs >> + * Copyright (C) 2020 Wilken Gottwalt <wilken.gottwalt@posteo.net> >> + */ >> + >> +#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 "sun8i_hwspinlock" >> + >> +#define SPINLOCK_BASE_ID 0 /* there is only one hwspinlock device per SoC */ >> +#define SPINLOCK_SYSSTATUS_REG 0x0000 >> +#define SPINLOCK_LOCK_REGN 0x0100 >> +#define SPINLOCK_NOTTAKEN 0 >> + >> +struct sun8i_hwspinlock_data { >> + struct hwspinlock_device *bank; >> + struct reset_control *reset; >> + struct clk *ahb_clk; >> + struct dentry *debugfs; >> + int nlocks; >> +}; >> + >> +#ifdef CONFIG_DEBUG_FS >> + >> +static int hwlocks_supported_show(struct seq_file *seqf, void *unused) >> +{ >> + struct sun8i_hwspinlock_data *priv = seqf->private; >> + >> + seq_printf(seqf, "%d\n", priv->nlocks); >> + >> + return 0; >> +} >> +DEFINE_SHOW_ATTRIBUTE(hwlocks_supported); >> + >> +static void sun8i_hwspinlock_debugfs_init(struct sun8i_hwspinlock_data *priv) >> +{ >> + priv->debugfs = debugfs_create_dir(DRIVER_NAME, NULL); > > debugfs_create_dir can return an error pointer, you should check that > and return the error code if it does > >> + debugfs_create_file("supported", 0444, priv->debugfs, priv, &hwlocks_supported_fops); > > And debugfs_create_file can fail as well
My understanding was that you're not supposed to check the return values of debugfs_create_* functions, because debugfs is just for debugging and shouldn't prevent the driver from loading.
>> +} >> + >> +#else >> + >> +static void sun8i_hwspinlock_debugfs_init(struct sun8i_hwspinlock_data *priv) >> +{ >> +} >> + >> +#endif >> + >> +static int sun8i_hwspinlock_trylock(struct hwspinlock *lock) >> +{ >> + void __iomem *lock_addr = lock->priv; >> + >> + return (readl(lock_addr) == SPINLOCK_NOTTAKEN); >> +} >> + >> +static void sun8i_hwspinlock_unlock(struct hwspinlock *lock) >> +{ >> + void __iomem *lock_addr = lock->priv; >> + >> + writel(SPINLOCK_NOTTAKEN, lock_addr); >> +} >> + >> +static const struct hwspinlock_ops sun8i_hwspinlock_ops = { >> + .trylock = sun8i_hwspinlock_trylock, >> + .unlock = sun8i_hwspinlock_unlock, >> +}; >> + >> +static void sun8i_hwspinlock_disable(void *data) >> +{ >> + struct sun8i_hwspinlock_data *priv = data; >> + >> + debugfs_remove_recursive(priv->debugfs); >> + reset_control_assert(priv->reset); >> + clk_disable_unprepare(priv->ahb_clk); >> +} >> + >> +static int sun8i_hwspinlock_probe(struct platform_device *pdev) >> +{ >> + struct sun8i_hwspinlock_data *priv; >> + struct hwspinlock *hwlock; >> + void __iomem *io_base; >> + u32 num_banks; >> + int err, i; >> + >> + io_base = devm_platform_ioremap_resource(pdev, SPINLOCK_BASE_ID); >> + if (IS_ERR(io_base)) >> + return PTR_ERR(io_base); >> + >> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); >> + if (!priv) >> + return -ENOMEM; >> + >> + priv->ahb_clk = devm_clk_get(&pdev->dev, "ahb"); >> + if (IS_ERR(priv->ahb_clk)) { >> + err = PTR_ERR(priv->ahb_clk); >> + dev_err(&pdev->dev, "unable to get AHB clock (%d)\n", err); >> + return err; >> + } >> + >> + priv->reset = devm_reset_control_get(&pdev->dev, "ahb"); >> + if (IS_ERR(priv->reset)) >> + return dev_err_probe(&pdev->dev, PTR_ERR(priv->reset), >> + "unable to get reset control\n"); >> + >> + 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_clk); >> + if (err) { >> + dev_err(&pdev->dev, "unable to prepare AHB clk (%d)\n", err); >> + return err; >> + } >> + >> + sun8i_hwspinlock_debugfs_init(priv); >> + >> + err = devm_add_action_or_reset(&pdev->dev, sun8i_hwspinlock_disable, priv); >> + if (err) { >> + dev_err(&pdev->dev, "unable to add disable action\n"); >> + return err; >> + } > > That part still doesn't really work: if clk_prepare_enable fails, you'll > end up removing the debugfs files that haven't been added yet, and > you'll disable the clock that hasn't been enabled. > > I'm not sure you need to be that smart: just add a label and a goto to > the proper cleaning stuff
I would also suggest implementing the driver's .remove callback instead of allocating additional memory for a devm action.
Samuel
> Maxime >
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