1 /*
2  * Janz MODULbus VMOD-TTL GPIO Driver
3  *
4  * Copyright (c) 2010 Ira W. Snyder <iws@ovro.caltech.edu>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the
8  * Free Software Foundation; either version 2 of the License, or (at your
9  * option) any later version.
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/init.h>
15 #include <linux/interrupt.h>
16 #include <linux/delay.h>
17 #include <linux/platform_device.h>
18 #include <linux/io.h>
19 #include <linux/gpio/driver.h>
20 #include <linux/slab.h>
21 #include <linux/bitops.h>
22 
23 #include <linux/mfd/janz.h>
24 
25 #define DRV_NAME "janz-ttl"
26 
27 #define PORTA_DIRECTION		0x23
28 #define PORTB_DIRECTION		0x2B
29 #define PORTC_DIRECTION		0x06
30 #define PORTA_IOCTL		0x24
31 #define PORTB_IOCTL		0x2C
32 #define PORTC_IOCTL		0x07
33 
34 #define MASTER_INT_CTL		0x00
35 #define MASTER_CONF_CTL		0x01
36 
37 #define CONF_PAE		BIT(2)
38 #define CONF_PBE		BIT(7)
39 #define CONF_PCE		BIT(4)
40 
41 struct ttl_control_regs {
42 	__be16 portc;
43 	__be16 portb;
44 	__be16 porta;
45 	__be16 control;
46 };
47 
48 struct ttl_module {
49 	struct gpio_chip gpio;
50 
51 	/* base address of registers */
52 	struct ttl_control_regs __iomem *regs;
53 
54 	u8 portc_shadow;
55 	u8 portb_shadow;
56 	u8 porta_shadow;
57 
58 	spinlock_t lock;
59 };
60 
ttl_get_value(struct gpio_chip * gpio,unsigned offset)61 static int ttl_get_value(struct gpio_chip *gpio, unsigned offset)
62 {
63 	struct ttl_module *mod = dev_get_drvdata(gpio->parent);
64 	u8 *shadow;
65 	int ret;
66 
67 	if (offset < 8) {
68 		shadow = &mod->porta_shadow;
69 	} else if (offset < 16) {
70 		shadow = &mod->portb_shadow;
71 		offset -= 8;
72 	} else {
73 		shadow = &mod->portc_shadow;
74 		offset -= 16;
75 	}
76 
77 	spin_lock(&mod->lock);
78 	ret = *shadow & BIT(offset);
79 	spin_unlock(&mod->lock);
80 	return !!ret;
81 }
82 
ttl_set_value(struct gpio_chip * gpio,unsigned offset,int value)83 static void ttl_set_value(struct gpio_chip *gpio, unsigned offset, int value)
84 {
85 	struct ttl_module *mod = dev_get_drvdata(gpio->parent);
86 	void __iomem *port;
87 	u8 *shadow;
88 
89 	if (offset < 8) {
90 		port = &mod->regs->porta;
91 		shadow = &mod->porta_shadow;
92 	} else if (offset < 16) {
93 		port = &mod->regs->portb;
94 		shadow = &mod->portb_shadow;
95 		offset -= 8;
96 	} else {
97 		port = &mod->regs->portc;
98 		shadow = &mod->portc_shadow;
99 		offset -= 16;
100 	}
101 
102 	spin_lock(&mod->lock);
103 	if (value)
104 		*shadow |= BIT(offset);
105 	else
106 		*shadow &= ~BIT(offset);
107 
108 	iowrite16be(*shadow, port);
109 	spin_unlock(&mod->lock);
110 }
111 
ttl_write_reg(struct ttl_module * mod,u8 reg,u16 val)112 static void ttl_write_reg(struct ttl_module *mod, u8 reg, u16 val)
113 {
114 	iowrite16be(reg, &mod->regs->control);
115 	iowrite16be(val, &mod->regs->control);
116 }
117 
ttl_setup_device(struct ttl_module * mod)118 static void ttl_setup_device(struct ttl_module *mod)
119 {
120 	/* reset the device to a known state */
121 	iowrite16be(0x0000, &mod->regs->control);
122 	iowrite16be(0x0001, &mod->regs->control);
123 	iowrite16be(0x0000, &mod->regs->control);
124 
125 	/* put all ports in open-drain mode */
126 	ttl_write_reg(mod, PORTA_IOCTL, 0x00ff);
127 	ttl_write_reg(mod, PORTB_IOCTL, 0x00ff);
128 	ttl_write_reg(mod, PORTC_IOCTL, 0x000f);
129 
130 	/* set all ports as outputs */
131 	ttl_write_reg(mod, PORTA_DIRECTION, 0x0000);
132 	ttl_write_reg(mod, PORTB_DIRECTION, 0x0000);
133 	ttl_write_reg(mod, PORTC_DIRECTION, 0x0000);
134 
135 	/* set all ports to drive zeroes */
136 	iowrite16be(0x0000, &mod->regs->porta);
137 	iowrite16be(0x0000, &mod->regs->portb);
138 	iowrite16be(0x0000, &mod->regs->portc);
139 
140 	/* enable all ports */
141 	ttl_write_reg(mod, MASTER_CONF_CTL, CONF_PAE | CONF_PBE | CONF_PCE);
142 }
143 
ttl_probe(struct platform_device * pdev)144 static int ttl_probe(struct platform_device *pdev)
145 {
146 	struct janz_platform_data *pdata;
147 	struct device *dev = &pdev->dev;
148 	struct ttl_module *mod;
149 	struct gpio_chip *gpio;
150 	struct resource *res;
151 	int ret;
152 
153 	pdata = dev_get_platdata(&pdev->dev);
154 	if (!pdata) {
155 		dev_err(dev, "no platform data\n");
156 		return -ENXIO;
157 	}
158 
159 	mod = devm_kzalloc(dev, sizeof(*mod), GFP_KERNEL);
160 	if (!mod)
161 		return -ENOMEM;
162 
163 	platform_set_drvdata(pdev, mod);
164 	spin_lock_init(&mod->lock);
165 
166 	/* get access to the MODULbus registers for this module */
167 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
168 	mod->regs = devm_ioremap_resource(dev, res);
169 	if (IS_ERR(mod->regs))
170 		return PTR_ERR(mod->regs);
171 
172 	ttl_setup_device(mod);
173 
174 	/* Initialize the GPIO data structures */
175 	gpio = &mod->gpio;
176 	gpio->parent = &pdev->dev;
177 	gpio->label = pdev->name;
178 	gpio->get = ttl_get_value;
179 	gpio->set = ttl_set_value;
180 	gpio->owner = THIS_MODULE;
181 
182 	/* request dynamic allocation */
183 	gpio->base = -1;
184 	gpio->ngpio = 20;
185 
186 	ret = devm_gpiochip_add_data(dev, gpio, NULL);
187 	if (ret) {
188 		dev_err(dev, "unable to add GPIO chip\n");
189 		return ret;
190 	}
191 
192 	return 0;
193 }
194 
195 static struct platform_driver ttl_driver = {
196 	.driver		= {
197 		.name	= DRV_NAME,
198 	},
199 	.probe		= ttl_probe,
200 };
201 
202 module_platform_driver(ttl_driver);
203 
204 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
205 MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver");
206 MODULE_LICENSE("GPL");
207 MODULE_ALIAS("platform:janz-ttl");
208