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// 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");
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