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 
37 struct ttl_control_regs {
38 	__be16 portc;
39 	__be16 portb;
40 	__be16 porta;
41 	__be16 control;
42 };
43 
44 struct 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 
ttl_get_value(struct gpio_chip * gpio,unsigned offset)57 static 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 
ttl_set_value(struct gpio_chip * gpio,unsigned offset,int value)79 static 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 
ttl_write_reg(struct ttl_module * mod,u8 reg,u16 val)108 static 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 
ttl_setup_device(struct ttl_module * mod)114 static 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 
ttl_probe(struct platform_device * pdev)140 static 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 
188 static struct platform_driver ttl_driver = {
189 	.driver		= {
190 		.name	= DRV_NAME,
191 	},
192 	.probe		= ttl_probe,
193 };
194 
195 module_platform_driver(ttl_driver);
196 
197 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
198 MODULE_DESCRIPTION("Janz MODULbus VMOD-TTL Driver");
199 MODULE_LICENSE("GPL");
200 MODULE_ALIAS("platform:janz-ttl");
201