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/drivers/gpio/gpio-janz-ttl.c

http://github.com/mirrors/linux
C | 200 lines | 148 code | 37 blank | 15 comment | 13 complexity | ec7abb2285c9bfffac6d1bbfe95215cd MD5 | raw file
  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Janz MODULbus VMOD-TTL GPIO Driver
  4 *
  5 * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu>
  6 */
  7
  8#include <linux/kernel.h>
  9#include <linux/module.h>
 10#include <linux/init.h>
 11#include <linux/interrupt.h>
 12#include <linux/delay.h>
 13#include <linux/platform_device.h>
 14#include <linux/io.h>
 15#include <linux/gpio/driver.h>
 16#include <linux/slab.h>
 17#include <linux/bitops.h>
 18
 19#include <linux/mfd/janz.h>
 20
 21#define DRV_NAME "janz-ttl"
 22
 23#define PORTA_DIRECTION		0x23
 24#define PORTB_DIRECTION		0x2B
 25#define PORTC_DIRECTION		0x06
 26#define PORTA_IOCTL		0x24
 27#define PORTB_IOCTL		0x2C
 28#define PORTC_IOCTL		0x07
 29
 30#define MASTER_INT_CTL		0x00
 31#define MASTER_CONF_CTL		0x01
 32
 33#define CONF_PAE		BIT(2)
 34#define CONF_PBE		BIT(7)
 35#define CONF_PCE		BIT(4)
 36
 37struct ttl_control_regs {
 38	__be16 portc;
 39	__be16 portb;
 40	__be16 porta;
 41	__be16 control;
 42};
 43
 44struct ttl_module {
 45	struct gpio_chip gpio;
 46
 47	/* base address of registers */
 48	struct ttl_control_regs __iomem *regs;
 49
 50	u8 portc_shadow;
 51	u8 portb_shadow;
 52	u8 porta_shadow;
 53
 54	spinlock_t lock;
 55};
 56
 57static int ttl_get_value(struct gpio_chip *gpio, unsigned offset)
 58{
 59	struct ttl_module *mod = dev_get_drvdata(gpio->parent);
 60	u8 *shadow;
 61	int ret;
 62
 63	if (offset < 8) {
 64		shadow = &mod->porta_shadow;
 65	} else if (offset < 16) {
 66		shadow = &mod->portb_shadow;
 67		offset -= 8;
 68	} else {
 69		shadow = &mod->portc_shadow;
 70		offset -= 16;
 71	}
 72
 73	spin_lock(&mod->lock);
 74	ret = *shadow & BIT(offset);
 75	spin_unlock(&mod->lock);
 76	return !!ret;
 77}
 78
 79static void ttl_set_value(struct gpio_chip *gpio, unsigned offset, int value)
 80{
 81	struct ttl_module *mod = dev_get_drvdata(gpio->parent);
 82	void __iomem *port;
 83	u8 *shadow;
 84
 85	if (offset < 8) {
 86		port = &mod->regs->porta;
 87		shadow = &mod->porta_shadow;
 88	} else if (offset < 16) {
 89		port = &mod->regs->portb;
 90		shadow = &mod->portb_shadow;
 91		offset -= 8;
 92	} else {
 93		port = &mod->regs->portc;
 94		shadow = &mod->portc_shadow;
 95		offset -= 16;
 96	}
 97
 98	spin_lock(&mod->lock);
 99	if (value)
100		*shadow |= BIT(offset);
101	else
102		*shadow &= ~BIT(offset);
103
104	iowrite16be(*shadow, port);
105	spin_unlock(&mod->lock);
106}
107
108static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val)
109{
110	iowrite16be(reg, &mod->regs->control);
111	iowrite16be(val, &mod->regs->control);
112}
113
114static void ttl_setup_device(struct ttl_module *mod)
115{
116	/* reset the device to a known state */
117	iowrite16be(0x0000, &mod->regs->control);
118	iowrite16be(0x0001, &mod->regs->control);
119	iowrite16be(0x0000, &mod->regs->control);
120
121	/* put all ports in open-drain mode */
122	ttl_write_reg(mod, PORTA_IOCTL, 0x00ff);
123	ttl_write_reg(mod, PORTB_IOCTL, 0x00ff);
124	ttl_write_reg(mod, PORTC_IOCTL, 0x000f);
125
126	/* set all ports as outputs */
127	ttl_write_reg(mod, PORTA_DIRECTION, 0x0000);
128	ttl_write_reg(mod, PORTB_DIRECTION, 0x0000);
129	ttl_write_reg(mod, PORTC_DIRECTION, 0x0000);
130
131	/* set all ports to drive zeroes */
132	iowrite16be(0x0000, &mod->regs->porta);
133	iowrite16be(0x0000, &mod->regs->portb);
134	iowrite16be(0x0000, &mod->regs->portc);
135
136	/* enable all ports */
137	ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE);
138}
139
140static int ttl_probe(struct platform_device *pdev)
141{
142	struct janz_platform_data *pdata;
143	struct ttl_module *mod;
144	struct gpio_chip *gpio;
145	int ret;
146
147	pdata = dev_get_platdata(&pdev->dev);
148	if (!pdata) {
149		dev_err(&pdev->dev, "no platform data\n");
150		return -ENXIO;
151	}
152
153	mod = devm_kzalloc(&pdev->dev, sizeof(*mod), GFP_KERNEL);
154	if (!mod)
155		return -ENOMEM;
156
157	platform_set_drvdata(pdev, mod);
158	spin_lock_init(&mod->lock);
159
160	/* get access to the MODULbus registers for this module */
161	mod->regs = devm_platform_ioremap_resource(pdev, 0);
162	if (IS_ERR(mod->regs))
163		return PTR_ERR(mod->regs);
164
165	ttl_setup_device(mod);
166
167	/* Initialize the GPIO data structures */
168	gpio = &mod->gpio;
169	gpio->parent = &pdev->dev;
170	gpio->label = pdev->name;
171	gpio->get = ttl_get_value;
172	gpio->set = ttl_set_value;
173	gpio->owner = THIS_MODULE;
174
175	/* request dynamic allocation */
176	gpio->base = -1;
177	gpio->ngpio = 20;
178
179	ret = devm_gpiochip_add_data(&pdev->dev, gpio, NULL);
180	if (ret) {
181		dev_err(&pdev->dev, "unable to add GPIO chip\n");
182		return ret;
183	}
184
185	return 0;
186}
187
188static struct platform_driver ttl_driver = {
189	.driver		= {
190		.name	= DRV_NAME,
191	},
192	.probe		= ttl_probe,
193};
194
195module_platform_driver(ttl_driver);
196
197MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
198MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver");
199MODULE_LICENSE("GPL");
200MODULE_ALIAS("platform:janz-ttl");