1 /*
2  * (C) Copyright 2009-2010
3  * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
4  *
5  * Portions Copyright (C) 2010 - 2016 Cavium, Inc.
6  *
7  * This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
8  *
9  * This file is licensed under the terms of the GNU General Public
10  * License version 2. This program is licensed "as is" without any
11  * warranty of any kind, whether express or implied.
12  */
13 
14 #include <linux/atomic.h>
15 #include <linux/delay.h>
16 #include <linux/i2c.h>
17 #include <linux/interrupt.h>
18 #include <linux/io.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/of.h>
22 #include <linux/platform_device.h>
23 #include <linux/sched.h>
24 #include <linux/slab.h>
25 
26 #include <asm/octeon/octeon.h>
27 #include "i2c-octeon-core.h"
28 
29 #define DRV_NAME "i2c-octeon"
30 
31 /**
32  * octeon_i2c_int_enable - enable the CORE interrupt
33  * @i2c: The struct octeon_i2c
34  *
35  * The interrupt will be asserted when there is non-STAT_IDLE state in
36  * the SW_TWSI_EOP_TWSI_STAT register.
37  */
38 static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
39 {
40 	octeon_i2c_write_int(i2c, TWSI_INT_CORE_EN);
41 }
42 
43 /* disable the CORE interrupt */
44 static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
45 {
46 	/* clear TS/ST/IFLG events */
47 	octeon_i2c_write_int(i2c, 0);
48 }
49 
50 /**
51  * octeon_i2c_int_enable78 - enable the CORE interrupt
52  * @i2c: The struct octeon_i2c
53  *
54  * The interrupt will be asserted when there is non-STAT_IDLE state in the
55  * SW_TWSI_EOP_TWSI_STAT register.
56  */
57 static void octeon_i2c_int_enable78(struct octeon_i2c *i2c)
58 {
59 	atomic_inc_return(&i2c->int_enable_cnt);
60 	enable_irq(i2c->irq);
61 }
62 
63 static void __octeon_i2c_irq_disable(atomic_t *cnt, int irq)
64 {
65 	int count;
66 
67 	/*
68 	 * The interrupt can be disabled in two places, but we only
69 	 * want to make the disable_irq_nosync() call once, so keep
70 	 * track with the atomic variable.
71 	 */
72 	count = atomic_dec_if_positive(cnt);
73 	if (count >= 0)
74 		disable_irq_nosync(irq);
75 }
76 
77 /* disable the CORE interrupt */
78 static void octeon_i2c_int_disable78(struct octeon_i2c *i2c)
79 {
80 	__octeon_i2c_irq_disable(&i2c->int_enable_cnt, i2c->irq);
81 }
82 
83 /**
84  * octeon_i2c_hlc_int_enable78 - enable the ST interrupt
85  * @i2c: The struct octeon_i2c
86  *
87  * The interrupt will be asserted when there is non-STAT_IDLE state in
88  * the SW_TWSI_EOP_TWSI_STAT register.
89  */
90 static void octeon_i2c_hlc_int_enable78(struct octeon_i2c *i2c)
91 {
92 	atomic_inc_return(&i2c->hlc_int_enable_cnt);
93 	enable_irq(i2c->hlc_irq);
94 }
95 
96 /* disable the ST interrupt */
97 static void octeon_i2c_hlc_int_disable78(struct octeon_i2c *i2c)
98 {
99 	__octeon_i2c_irq_disable(&i2c->hlc_int_enable_cnt, i2c->hlc_irq);
100 }
101 
102 /* HLC interrupt service routine */
103 static irqreturn_t octeon_i2c_hlc_isr78(int irq, void *dev_id)
104 {
105 	struct octeon_i2c *i2c = dev_id;
106 
107 	i2c->hlc_int_disable(i2c);
108 	wake_up(&i2c->queue);
109 
110 	return IRQ_HANDLED;
111 }
112 
113 static void octeon_i2c_hlc_int_enable(struct octeon_i2c *i2c)
114 {
115 	octeon_i2c_write_int(i2c, TWSI_INT_ST_EN);
116 }
117 
118 static u32 octeon_i2c_functionality(struct i2c_adapter *adap)
119 {
120 	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) |
121 	       I2C_FUNC_SMBUS_READ_BLOCK_DATA | I2C_SMBUS_BLOCK_PROC_CALL;
122 }
123 
124 static const struct i2c_algorithm octeon_i2c_algo = {
125 	.master_xfer = octeon_i2c_xfer,
126 	.functionality = octeon_i2c_functionality,
127 };
128 
129 static const struct i2c_adapter octeon_i2c_ops = {
130 	.owner = THIS_MODULE,
131 	.name = "OCTEON adapter",
132 	.algo = &octeon_i2c_algo,
133 };
134 
135 static int octeon_i2c_probe(struct platform_device *pdev)
136 {
137 	struct device_node *node = pdev->dev.of_node;
138 	int irq, result = 0, hlc_irq = 0;
139 	struct resource *res_mem;
140 	struct octeon_i2c *i2c;
141 	bool cn78xx_style;
142 
143 	cn78xx_style = of_device_is_compatible(node, "cavium,octeon-7890-twsi");
144 	if (cn78xx_style) {
145 		hlc_irq = platform_get_irq(pdev, 0);
146 		if (hlc_irq < 0)
147 			return hlc_irq;
148 
149 		irq = platform_get_irq(pdev, 2);
150 		if (irq < 0)
151 			return irq;
152 	} else {
153 		/* All adaptors have an irq.  */
154 		irq = platform_get_irq(pdev, 0);
155 		if (irq < 0)
156 			return irq;
157 	}
158 
159 	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
160 	if (!i2c) {
161 		result = -ENOMEM;
162 		goto out;
163 	}
164 	i2c->dev = &pdev->dev;
165 
166 	i2c->roff.sw_twsi = 0x00;
167 	i2c->roff.twsi_int = 0x10;
168 	i2c->roff.sw_twsi_ext = 0x18;
169 
170 	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
171 	i2c->twsi_base = devm_ioremap_resource(&pdev->dev, res_mem);
172 	if (IS_ERR(i2c->twsi_base)) {
173 		result = PTR_ERR(i2c->twsi_base);
174 		goto out;
175 	}
176 
177 	/*
178 	 * "clock-rate" is a legacy binding, the official binding is
179 	 * "clock-frequency".  Try the official one first and then
180 	 * fall back if it doesn't exist.
181 	 */
182 	if (of_property_read_u32(node, "clock-frequency", &i2c->twsi_freq) &&
183 	    of_property_read_u32(node, "clock-rate", &i2c->twsi_freq)) {
184 		dev_err(i2c->dev,
185 			"no I2C 'clock-rate' or 'clock-frequency' property\n");
186 		result = -ENXIO;
187 		goto out;
188 	}
189 
190 	i2c->sys_freq = octeon_get_io_clock_rate();
191 
192 	init_waitqueue_head(&i2c->queue);
193 
194 	i2c->irq = irq;
195 
196 	if (cn78xx_style) {
197 		i2c->hlc_irq = hlc_irq;
198 
199 		i2c->int_enable = octeon_i2c_int_enable78;
200 		i2c->int_disable = octeon_i2c_int_disable78;
201 		i2c->hlc_int_enable = octeon_i2c_hlc_int_enable78;
202 		i2c->hlc_int_disable = octeon_i2c_hlc_int_disable78;
203 
204 		irq_set_status_flags(i2c->irq, IRQ_NOAUTOEN);
205 		irq_set_status_flags(i2c->hlc_irq, IRQ_NOAUTOEN);
206 
207 		result = devm_request_irq(&pdev->dev, i2c->hlc_irq,
208 					  octeon_i2c_hlc_isr78, 0,
209 					  DRV_NAME, i2c);
210 		if (result < 0) {
211 			dev_err(i2c->dev, "failed to attach interrupt\n");
212 			goto out;
213 		}
214 	} else {
215 		i2c->int_enable = octeon_i2c_int_enable;
216 		i2c->int_disable = octeon_i2c_int_disable;
217 		i2c->hlc_int_enable = octeon_i2c_hlc_int_enable;
218 		i2c->hlc_int_disable = octeon_i2c_int_disable;
219 	}
220 
221 	result = devm_request_irq(&pdev->dev, i2c->irq,
222 				  octeon_i2c_isr, 0, DRV_NAME, i2c);
223 	if (result < 0) {
224 		dev_err(i2c->dev, "failed to attach interrupt\n");
225 		goto out;
226 	}
227 
228 	if (OCTEON_IS_MODEL(OCTEON_CN38XX))
229 		i2c->broken_irq_check = true;
230 
231 	result = octeon_i2c_init_lowlevel(i2c);
232 	if (result) {
233 		dev_err(i2c->dev, "init low level failed\n");
234 		goto  out;
235 	}
236 
237 	octeon_i2c_set_clock(i2c);
238 
239 	i2c->adap = octeon_i2c_ops;
240 	i2c->adap.timeout = msecs_to_jiffies(2);
241 	i2c->adap.retries = 5;
242 	i2c->adap.bus_recovery_info = &octeon_i2c_recovery_info;
243 	i2c->adap.dev.parent = &pdev->dev;
244 	i2c->adap.dev.of_node = node;
245 	i2c_set_adapdata(&i2c->adap, i2c);
246 	platform_set_drvdata(pdev, i2c);
247 
248 	result = i2c_add_adapter(&i2c->adap);
249 	if (result < 0)
250 		goto out;
251 	dev_info(i2c->dev, "probed\n");
252 	return 0;
253 
254 out:
255 	return result;
256 };
257 
258 static int octeon_i2c_remove(struct platform_device *pdev)
259 {
260 	struct octeon_i2c *i2c = platform_get_drvdata(pdev);
261 
262 	i2c_del_adapter(&i2c->adap);
263 	return 0;
264 };
265 
266 static const struct of_device_id octeon_i2c_match[] = {
267 	{ .compatible = "cavium,octeon-3860-twsi", },
268 	{ .compatible = "cavium,octeon-7890-twsi", },
269 	{},
270 };
271 MODULE_DEVICE_TABLE(of, octeon_i2c_match);
272 
273 static struct platform_driver octeon_i2c_driver = {
274 	.probe		= octeon_i2c_probe,
275 	.remove		= octeon_i2c_remove,
276 	.driver		= {
277 		.name	= DRV_NAME,
278 		.of_match_table = octeon_i2c_match,
279 	},
280 };
281 
282 module_platform_driver(octeon_i2c_driver);
283 
284 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
285 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
286 MODULE_LICENSE("GPL");
287