Messages in this thread Patch in this message | | | From | Baolin Wang <> | Subject | [PATCH 2/2] soc: sprd: Add Spreadtrum special bits updating support | Date | Fri, 17 Apr 2020 10:14:15 +0800 |
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The spreadtrum platform uses a special set/clear method to update registers' bits, which can remove the race of updating the global registers between the multiple subsystems. Thus we can register a physical regmap bus into syscon core to support this.
Signed-off-by: Baolin Wang <baolin.wang7@gmail.com> --- drivers/soc/Kconfig | 1 + drivers/soc/Makefile | 1 + drivers/soc/sprd/Kconfig | 16 +++++++ drivers/soc/sprd/Makefile | 2 + drivers/soc/sprd/sprd_syscon.c | 82 ++++++++++++++++++++++++++++++++++ 5 files changed, 102 insertions(+) create mode 100644 drivers/soc/sprd/Kconfig create mode 100644 drivers/soc/sprd/Makefile create mode 100644 drivers/soc/sprd/sprd_syscon.c
diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig index 425ab6f7e375..8cfbf2dc518d 100644 --- a/drivers/soc/Kconfig +++ b/drivers/soc/Kconfig @@ -23,5 +23,6 @@ source "drivers/soc/versatile/Kconfig" source "drivers/soc/xilinx/Kconfig" source "drivers/soc/zte/Kconfig" source "drivers/soc/kendryte/Kconfig" +source "drivers/soc/sprd/Kconfig" endmenu diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile index 36452bed86ef..7d156a6dd536 100644 --- a/drivers/soc/Makefile +++ b/drivers/soc/Makefile @@ -29,3 +29,4 @@ obj-$(CONFIG_PLAT_VERSATILE) += versatile/ obj-y += xilinx/ obj-$(CONFIG_ARCH_ZX) += zte/ obj-$(CONFIG_SOC_KENDRYTE) += kendryte/ +obj-$(CONFIG_ARCH_SPRD) += sprd/ diff --git a/drivers/soc/sprd/Kconfig b/drivers/soc/sprd/Kconfig new file mode 100644 index 000000000000..38d1f5971a28 --- /dev/null +++ b/drivers/soc/sprd/Kconfig @@ -0,0 +1,16 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# SPRD SoC drivers +# + +menu "Spreadtrum SoC drivers" + depends on ARCH_SPRD || COMPILE_TEST + +config SPRD_SYSCON + tristate "Spreadtrum syscon support" + depends on ARCH_SPRD || COMPILE_TEST + help + Say yes here to add support for the Spreadtrum syscon driver, + which is used to implement the atomic method of bits updating. + +endmenu diff --git a/drivers/soc/sprd/Makefile b/drivers/soc/sprd/Makefile new file mode 100644 index 000000000000..4d7715553cf6 --- /dev/null +++ b/drivers/soc/sprd/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_SPRD_SYSCON) += sprd_syscon.o diff --git a/drivers/soc/sprd/sprd_syscon.c b/drivers/soc/sprd/sprd_syscon.c new file mode 100644 index 000000000000..9b98127f1adb --- /dev/null +++ b/drivers/soc/sprd/sprd_syscon.c @@ -0,0 +1,82 @@ +//SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020 Spreadtrum Communications Inc. + */ +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/mfd/syscon.h> +#include <linux/regmap.h> + +#define SPRD_REG_SET_OFFSET 0x1000 +#define SPRD_REG_CLR_OFFSET 0x2000 + +/* + * The Spreadtrum platform defines a special set/clear method to update + * registers' bits, which means it can write values to the register's SET + * address (offset is 0x1000) to set bits, and write values to the register's + * CLEAR address (offset is 0x2000) to clear bits. + * + * This set/clear method can help to remove the race of accessing the global + * registers between the multiple subsystems instead of using hardware + * spinlocks. + * + * Note: there is a potential risk when users want to set and clear bits + * at the same time, since the set/clear method will always do bits setting + * before bits clearing, which may cause some unexpected results if the + * operation sequence is strict. Thus we recommend that do not set and + * clear bits at the same time if you are not sure the results. + */ +static int sprd_syscon_update_bits(void *context, unsigned int reg, + unsigned int mask, unsigned int val) +{ + void __iomem *base = context; + unsigned int set, clr; + + set = val & mask; + clr = ~set & mask; + + if (set) + writel(set, base + reg + SPRD_REG_SET_OFFSET); + + if (clr) + writel(clr, base + reg + SPRD_REG_CLR_OFFSET); + + return 0; +} + +static int sprd_syscon_read(void *context, unsigned int reg, unsigned int *val) +{ + void __iomem *base = context; + + *val = readl(base + reg); + return 0; +} + +static int sprd_syscon_write(void *context, unsigned int reg, unsigned int val) +{ + void __iomem *base = context; + + writel(val, base + reg); + return 0; +} + +static struct regmap_bus sprd_syscon_regmap = { + .fast_io = true, + .reg_write = sprd_syscon_write, + .reg_read = sprd_syscon_read, + .reg_update_bits = sprd_syscon_update_bits, + .val_format_endian_default = REGMAP_ENDIAN_LITTLE, +}; + +static int sprd_syscon_init(void) +{ + syscon_register_phys_regmap_bus(&sprd_syscon_regmap); + + return 0; +} +core_initcall_sync(sprd_syscon_init); + +MODULE_DESCRIPTION("Spreadtrum syscon support"); +MODULE_AUTHOR("Baolin Wang <baolin.wang@unisoc.com>"); +MODULE_LICENSE("GPL v2"); -- 2.17.1
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