diff options
Diffstat (limited to 'drivers/gpio')
| -rw-r--r-- | drivers/gpio/Kconfig | 8 | ||||
| -rw-r--r-- | drivers/gpio/Makefile | 1 | ||||
| -rw-r--r-- | drivers/gpio/gpio-xtensa.c | 163 |
3 files changed, 172 insertions, 0 deletions
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index 4127f68412eb..02e8d5350f8b 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -288,6 +288,14 @@ config GPIO_XILINX help Say yes here to support the Xilinx FPGA GPIO device +config GPIO_XTENSA + bool "Xtensa GPIO32 support" + depends on XTENSA + depends on !SMP + help + Say yes here to support the Xtensa internal GPIO32 IMPWIRE (input) + and EXPSTATE (output) ports + config GPIO_VR41XX tristate "NEC VR4100 series General-purpose I/O Uint support" depends on CPU_VR41XX diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index ee95154cb1d2..699e7cd96584 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -96,3 +96,4 @@ obj-$(CONFIG_GPIO_WM831X) += gpio-wm831x.o obj-$(CONFIG_GPIO_WM8350) += gpio-wm8350.o obj-$(CONFIG_GPIO_WM8994) += gpio-wm8994.o obj-$(CONFIG_GPIO_XILINX) += gpio-xilinx.o +obj-$(CONFIG_GPIO_XTENSA) += gpio-xtensa.o diff --git a/drivers/gpio/gpio-xtensa.c b/drivers/gpio/gpio-xtensa.c new file mode 100644 index 000000000000..1d136eceda62 --- /dev/null +++ b/drivers/gpio/gpio-xtensa.c @@ -0,0 +1,163 @@ +/* + * Copyright (C) 2013 TangoTec Ltd. + * Author: Baruch Siach <baruch@tkos.co.il> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * Driver for the Xtensa LX4 GPIO32 Option + * + * Documentation: Xtensa LX4 Microprocessor Data Book, Section 2.22 + * + * GPIO32 is a standard optional extension to the Xtensa architecture core that + * provides preconfigured output and input ports for intra SoC signaling. The + * GPIO32 option is implemented as 32bit Tensilica Instruction Extension (TIE) + * output state called EXPSTATE, and 32bit input wire called IMPWIRE. This + * driver treats input and output states as two distinct devices. + * + * Access to GPIO32 specific instructions is controlled by the CPENABLE + * (Coprocessor Enable Bits) register. By default Xtensa Linux startup code + * disables access to all coprocessors. This driver sets the CPENABLE bit + * corresponding to GPIO32 before any GPIO32 specific instruction, and restores + * CPENABLE state after that. + * + * This driver is currently incompatible with SMP. The GPIO32 extension is not + * guaranteed to be available in all cores. Moreover, each core controls a + * different set of IO wires. A theoretical SMP aware version of this driver + * would need to have a per core workqueue to do the actual GPIO manipulation. + */ + +#include <linux/err.h> +#include <linux/module.h> +#include <linux/gpio.h> +#include <linux/bitops.h> +#include <linux/platform_device.h> + +#include <asm/coprocessor.h> /* CPENABLE read/write macros */ + +#ifndef XCHAL_CP_ID_XTIOP +#error GPIO32 option is not enabled for your xtensa core variant +#endif + +static inline unsigned long enable_cp(unsigned long *cpenable) +{ + unsigned long flags; + + local_irq_save(flags); + RSR_CPENABLE(*cpenable); + WSR_CPENABLE(*cpenable | BIT(XCHAL_CP_ID_XTIOP)); + + return flags; +} + +static inline void disable_cp(unsigned long flags, unsigned long cpenable) +{ + WSR_CPENABLE(cpenable); + local_irq_restore(flags); +} + +static int xtensa_impwire_get_direction(struct gpio_chip *gc, unsigned offset) +{ + return 1; /* input only */ +} + +static int xtensa_impwire_get_value(struct gpio_chip *gc, unsigned offset) +{ + unsigned long flags, saved_cpenable; + u32 impwire; + + flags = enable_cp(&saved_cpenable); + __asm__ __volatile__("read_impwire %0" : "=a" (impwire)); + disable_cp(flags, saved_cpenable); + + return !!(impwire & BIT(offset)); +} + +static void xtensa_impwire_set_value(struct gpio_chip *gc, unsigned offset, + int value) +{ + BUG(); /* output only; should never be called */ +} + +static int xtensa_expstate_get_direction(struct gpio_chip *gc, unsigned offset) +{ + return 0; /* output only */ +} + +static int xtensa_expstate_get_value(struct gpio_chip *gc, unsigned offset) +{ + unsigned long flags, saved_cpenable; + u32 expstate; + + flags = enable_cp(&saved_cpenable); + __asm__ __volatile__("rur.expstate %0" : "=a" (expstate)); + disable_cp(flags, saved_cpenable); + + return !!(expstate & BIT(offset)); +} + +static void xtensa_expstate_set_value(struct gpio_chip *gc, unsigned offset, + int value) +{ + unsigned long flags, saved_cpenable; + u32 mask = BIT(offset); + u32 val = value ? BIT(offset) : 0; + + flags = enable_cp(&saved_cpenable); + __asm__ __volatile__("wrmsk_expstate %0, %1" + :: "a" (val), "a" (mask)); + disable_cp(flags, saved_cpenable); +} + +static struct gpio_chip impwire_chip = { + .label = "impwire", + .base = -1, + .ngpio = 32, + .get_direction = xtensa_impwire_get_direction, + .get = xtensa_impwire_get_value, + .set = xtensa_impwire_set_value, +}; + +static struct gpio_chip expstate_chip = { + .label = "expstate", + .base = -1, + .ngpio = 32, + .get_direction = xtensa_expstate_get_direction, + .get = xtensa_expstate_get_value, + .set = xtensa_expstate_set_value, +}; + +static int xtensa_gpio_probe(struct platform_device *pdev) +{ + int ret; + + ret = gpiochip_add(&impwire_chip); + if (ret) + return ret; + return gpiochip_add(&expstate_chip); +} + +static struct platform_driver xtensa_gpio_driver = { + .driver = { + .name = "xtensa-gpio", + .owner = THIS_MODULE, + }, + .probe = xtensa_gpio_probe, +}; + +static int __init xtensa_gpio_init(void) +{ + struct platform_device *pdev; + + pdev = platform_device_register_simple("xtensa-gpio", 0, NULL, 0); + if (IS_ERR(pdev)) + return PTR_ERR(pdev); + + return platform_driver_register(&xtensa_gpio_driver); +} +device_initcall(xtensa_gpio_init); + +MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); +MODULE_DESCRIPTION("Xtensa LX4 GPIO32 driver"); +MODULE_LICENSE("GPL"); |