diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/gpio/gpio-janz-ttl.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-janz-ttl.c b/drivers/gpio/gpio-janz-ttl.c new file mode 100644 index 000000000..cdf50e4ea --- /dev/null +++ b/drivers/gpio/gpio-janz-ttl.c @@ -0,0 +1,200 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Janz MODULbus VMOD-TTL GPIO Driver + * + * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu> + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/delay.h> +#include <linux/platform_device.h> +#include <linux/io.h> +#include <linux/gpio/driver.h> +#include <linux/slab.h> +#include <linux/bitops.h> + +#include <linux/mfd/janz.h> + +#define DRV_NAME "janz-ttl" + +#define PORTA_DIRECTION 0x23 +#define PORTB_DIRECTION 0x2B +#define PORTC_DIRECTION 0x06 +#define PORTA_IOCTL 0x24 +#define PORTB_IOCTL 0x2C +#define PORTC_IOCTL 0x07 + +#define MASTER_INT_CTL 0x00 +#define MASTER_CONF_CTL 0x01 + +#define CONF_PAE BIT(2) +#define CONF_PBE BIT(7) +#define CONF_PCE BIT(4) + +struct ttl_control_regs { + __be16 portc; + __be16 portb; + __be16 porta; + __be16 control; +}; + +struct ttl_module { + struct gpio_chip gpio; + + /* base address of registers */ + struct ttl_control_regs __iomem *regs; + + u8 portc_shadow; + u8 portb_shadow; + u8 porta_shadow; + + spinlock_t lock; +}; + +static int ttl_get_value(struct gpio_chip *gpio, unsigned offset) +{ + struct ttl_module *mod = dev_get_drvdata(gpio->parent); + u8 *shadow; + int ret; + + if (offset < 8) { + shadow = &mod->porta_shadow; + } else if (offset < 16) { + shadow = &mod->portb_shadow; + offset -= 8; + } else { + shadow = &mod->portc_shadow; + offset -= 16; + } + + spin_lock(&mod->lock); + ret = *shadow & BIT(offset); + spin_unlock(&mod->lock); + return !!ret; +} + +static void ttl_set_value(struct gpio_chip *gpio, unsigned offset, int value) +{ + struct ttl_module *mod = dev_get_drvdata(gpio->parent); + void __iomem *port; + u8 *shadow; + + if (offset < 8) { + port = &mod->regs->porta; + shadow = &mod->porta_shadow; + } else if (offset < 16) { + port = &mod->regs->portb; + shadow = &mod->portb_shadow; + offset -= 8; + } else { + port = &mod->regs->portc; + shadow = &mod->portc_shadow; + offset -= 16; + } + + spin_lock(&mod->lock); + if (value) + *shadow |= BIT(offset); + else + *shadow &= ~BIT(offset); + + iowrite16be(*shadow, port); + spin_unlock(&mod->lock); +} + +static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val) +{ + iowrite16be(reg, &mod->regs->control); + iowrite16be(val, &mod->regs->control); +} + +static void ttl_setup_device(struct ttl_module *mod) +{ + /* reset the device to a known state */ + iowrite16be(0x0000, &mod->regs->control); + iowrite16be(0x0001, &mod->regs->control); + iowrite16be(0x0000, &mod->regs->control); + + /* put all ports in open-drain mode */ + ttl_write_reg(mod, PORTA_IOCTL, 0x00ff); + ttl_write_reg(mod, PORTB_IOCTL, 0x00ff); + ttl_write_reg(mod, PORTC_IOCTL, 0x000f); + + /* set all ports as outputs */ + ttl_write_reg(mod, PORTA_DIRECTION, 0x0000); + ttl_write_reg(mod, PORTB_DIRECTION, 0x0000); + ttl_write_reg(mod, PORTC_DIRECTION, 0x0000); + + /* set all ports to drive zeroes */ + iowrite16be(0x0000, &mod->regs->porta); + iowrite16be(0x0000, &mod->regs->portb); + iowrite16be(0x0000, &mod->regs->portc); + + /* enable all ports */ + ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE); +} + +static int ttl_probe(struct platform_device *pdev) +{ + struct janz_platform_data *pdata; + struct ttl_module *mod; + struct gpio_chip *gpio; + int ret; + + pdata = dev_get_platdata(&pdev->dev); + if (!pdata) { + dev_err(&pdev->dev, "no platform data\n"); + return -ENXIO; + } + + mod = devm_kzalloc(&pdev->dev, sizeof(*mod), GFP_KERNEL); + if (!mod) + return -ENOMEM; + + platform_set_drvdata(pdev, mod); + spin_lock_init(&mod->lock); + + /* get access to the MODULbus registers for this module */ + mod->regs = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(mod->regs)) + return PTR_ERR(mod->regs); + + ttl_setup_device(mod); + + /* Initialize the GPIO data structures */ + gpio = &mod->gpio; + gpio->parent = &pdev->dev; + gpio->label = pdev->name; + gpio->get = ttl_get_value; + gpio->set = ttl_set_value; + gpio->owner = THIS_MODULE; + + /* request dynamic allocation */ + gpio->base = -1; + gpio->ngpio = 20; + + ret = devm_gpiochip_add_data(&pdev->dev, gpio, NULL); + if (ret) { + dev_err(&pdev->dev, "unable to add GPIO chip\n"); + return ret; + } + + return 0; +} + +static struct platform_driver ttl_driver = { + .driver = { + .name = DRV_NAME, + }, + .probe = ttl_probe, +}; + +module_platform_driver(ttl_driver); + +MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>"); +MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("platform:janz-ttl"); |