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3e833490 BB |
1 | /* |
2 | * P2WI (Push-Pull Two Wire Interface) bus driver. | |
3 | * | |
4 | * Author: Boris BREZILLON <boris.brezillon@free-electrons.com> | |
5 | * | |
6 | * This file is licensed under the terms of the GNU General Public License | |
7 | * version 2. This program is licensed "as is" without any warranty of any | |
8 | * kind, whether express or implied. | |
9 | * | |
10 | * The P2WI controller looks like an SMBus controller which only supports byte | |
11 | * data transfers. But, it differs from standard SMBus protocol on several | |
12 | * aspects: | |
13 | * - it supports only one slave device, and thus drop the address field | |
14 | * - it adds a parity bit every 8bits of data | |
15 | * - only one read access is required to read a byte (instead of a write | |
16 | * followed by a read access in standard SMBus protocol) | |
17 | * - there's no Ack bit after each byte transfer | |
18 | * | |
19 | * This means this bus cannot be used to interface with standard SMBus | |
20 | * devices (the only known device to support this interface is the AXP221 | |
21 | * PMIC). | |
22 | * | |
23 | */ | |
24 | #include <linux/clk.h> | |
3e833490 BB |
25 | #include <linux/i2c.h> |
26 | #include <linux/io.h> | |
27 | #include <linux/interrupt.h> | |
28 | #include <linux/module.h> | |
29 | #include <linux/of.h> | |
30 | #include <linux/platform_device.h> | |
31 | #include <linux/reset.h> | |
32 | ||
33 | ||
34 | /* P2WI registers */ | |
35 | #define P2WI_CTRL 0x0 | |
36 | #define P2WI_CCR 0x4 | |
37 | #define P2WI_INTE 0x8 | |
38 | #define P2WI_INTS 0xc | |
39 | #define P2WI_DADDR0 0x10 | |
40 | #define P2WI_DADDR1 0x14 | |
41 | #define P2WI_DLEN 0x18 | |
42 | #define P2WI_DATA0 0x1c | |
43 | #define P2WI_DATA1 0x20 | |
44 | #define P2WI_LCR 0x24 | |
45 | #define P2WI_PMCR 0x28 | |
46 | ||
47 | /* CTRL fields */ | |
48 | #define P2WI_CTRL_START_TRANS BIT(7) | |
49 | #define P2WI_CTRL_ABORT_TRANS BIT(6) | |
50 | #define P2WI_CTRL_GLOBAL_INT_ENB BIT(1) | |
51 | #define P2WI_CTRL_SOFT_RST BIT(0) | |
52 | ||
53 | /* CLK CTRL fields */ | |
54 | #define P2WI_CCR_SDA_OUT_DELAY(v) (((v) & 0x7) << 8) | |
55 | #define P2WI_CCR_MAX_CLK_DIV 0xff | |
56 | #define P2WI_CCR_CLK_DIV(v) ((v) & P2WI_CCR_MAX_CLK_DIV) | |
57 | ||
58 | /* STATUS fields */ | |
59 | #define P2WI_INTS_TRANS_ERR_ID(v) (((v) >> 8) & 0xff) | |
60 | #define P2WI_INTS_LOAD_BSY BIT(2) | |
61 | #define P2WI_INTS_TRANS_ERR BIT(1) | |
62 | #define P2WI_INTS_TRANS_OVER BIT(0) | |
63 | ||
64 | /* DATA LENGTH fields*/ | |
65 | #define P2WI_DLEN_READ BIT(4) | |
66 | #define P2WI_DLEN_DATA_LENGTH(v) ((v - 1) & 0x7) | |
67 | ||
68 | /* LINE CTRL fields*/ | |
69 | #define P2WI_LCR_SCL_STATE BIT(5) | |
70 | #define P2WI_LCR_SDA_STATE BIT(4) | |
71 | #define P2WI_LCR_SCL_CTL BIT(3) | |
72 | #define P2WI_LCR_SCL_CTL_EN BIT(2) | |
73 | #define P2WI_LCR_SDA_CTL BIT(1) | |
74 | #define P2WI_LCR_SDA_CTL_EN BIT(0) | |
75 | ||
76 | /* PMU MODE CTRL fields */ | |
77 | #define P2WI_PMCR_PMU_INIT_SEND BIT(31) | |
78 | #define P2WI_PMCR_PMU_INIT_DATA(v) (((v) & 0xff) << 16) | |
79 | #define P2WI_PMCR_PMU_MODE_REG(v) (((v) & 0xff) << 8) | |
80 | #define P2WI_PMCR_PMU_DEV_ADDR(v) ((v) & 0xff) | |
81 | ||
82 | #define P2WI_MAX_FREQ 6000000 | |
83 | ||
84 | struct p2wi { | |
85 | struct i2c_adapter adapter; | |
86 | struct completion complete; | |
87 | unsigned int status; | |
88 | void __iomem *regs; | |
89 | struct clk *clk; | |
90 | struct reset_control *rstc; | |
91 | int slave_addr; | |
92 | }; | |
93 | ||
94 | static irqreturn_t p2wi_interrupt(int irq, void *dev_id) | |
95 | { | |
96 | struct p2wi *p2wi = dev_id; | |
97 | unsigned long status; | |
98 | ||
99 | status = readl(p2wi->regs + P2WI_INTS); | |
100 | p2wi->status = status; | |
101 | ||
102 | /* Clear interrupts */ | |
103 | status &= (P2WI_INTS_LOAD_BSY | P2WI_INTS_TRANS_ERR | | |
104 | P2WI_INTS_TRANS_OVER); | |
105 | writel(status, p2wi->regs + P2WI_INTS); | |
106 | ||
107 | complete(&p2wi->complete); | |
108 | ||
109 | return IRQ_HANDLED; | |
110 | } | |
111 | ||
112 | static u32 p2wi_functionality(struct i2c_adapter *adap) | |
113 | { | |
114 | return I2C_FUNC_SMBUS_BYTE_DATA; | |
115 | } | |
116 | ||
117 | static int p2wi_smbus_xfer(struct i2c_adapter *adap, u16 addr, | |
118 | unsigned short flags, char read_write, | |
119 | u8 command, int size, union i2c_smbus_data *data) | |
120 | { | |
121 | struct p2wi *p2wi = i2c_get_adapdata(adap); | |
122 | unsigned long dlen = P2WI_DLEN_DATA_LENGTH(1); | |
123 | ||
124 | if (p2wi->slave_addr >= 0 && addr != p2wi->slave_addr) { | |
125 | dev_err(&adap->dev, "invalid P2WI address\n"); | |
126 | return -EINVAL; | |
127 | } | |
128 | ||
129 | if (!data) | |
130 | return -EINVAL; | |
131 | ||
132 | writel(command, p2wi->regs + P2WI_DADDR0); | |
133 | ||
134 | if (read_write == I2C_SMBUS_READ) | |
135 | dlen |= P2WI_DLEN_READ; | |
136 | else | |
137 | writel(data->byte, p2wi->regs + P2WI_DATA0); | |
138 | ||
139 | writel(dlen, p2wi->regs + P2WI_DLEN); | |
140 | ||
141 | if (readl(p2wi->regs + P2WI_CTRL) & P2WI_CTRL_START_TRANS) { | |
142 | dev_err(&adap->dev, "P2WI bus busy\n"); | |
143 | return -EBUSY; | |
144 | } | |
145 | ||
146 | reinit_completion(&p2wi->complete); | |
147 | ||
148 | writel(P2WI_INTS_LOAD_BSY | P2WI_INTS_TRANS_ERR | P2WI_INTS_TRANS_OVER, | |
149 | p2wi->regs + P2WI_INTE); | |
150 | ||
151 | writel(P2WI_CTRL_START_TRANS | P2WI_CTRL_GLOBAL_INT_ENB, | |
152 | p2wi->regs + P2WI_CTRL); | |
153 | ||
154 | wait_for_completion(&p2wi->complete); | |
155 | ||
156 | if (p2wi->status & P2WI_INTS_LOAD_BSY) { | |
157 | dev_err(&adap->dev, "P2WI bus busy\n"); | |
158 | return -EBUSY; | |
159 | } | |
160 | ||
161 | if (p2wi->status & P2WI_INTS_TRANS_ERR) { | |
162 | dev_err(&adap->dev, "P2WI bus xfer error\n"); | |
163 | return -ENXIO; | |
164 | } | |
165 | ||
166 | if (read_write == I2C_SMBUS_READ) | |
167 | data->byte = readl(p2wi->regs + P2WI_DATA0); | |
168 | ||
169 | return 0; | |
170 | } | |
171 | ||
172 | static const struct i2c_algorithm p2wi_algo = { | |
173 | .smbus_xfer = p2wi_smbus_xfer, | |
174 | .functionality = p2wi_functionality, | |
175 | }; | |
176 | ||
177 | static const struct of_device_id p2wi_of_match_table[] = { | |
178 | { .compatible = "allwinner,sun6i-a31-p2wi" }, | |
179 | {} | |
180 | }; | |
181 | MODULE_DEVICE_TABLE(of, p2wi_of_match_table); | |
182 | ||
183 | static int p2wi_probe(struct platform_device *pdev) | |
184 | { | |
185 | struct device *dev = &pdev->dev; | |
186 | struct device_node *np = dev->of_node; | |
187 | struct device_node *childnp; | |
188 | unsigned long parent_clk_freq; | |
189 | u32 clk_freq = 100000; | |
190 | struct resource *r; | |
191 | struct p2wi *p2wi; | |
192 | u32 slave_addr; | |
193 | int clk_div; | |
194 | int irq; | |
195 | int ret; | |
196 | ||
197 | of_property_read_u32(np, "clock-frequency", &clk_freq); | |
198 | if (clk_freq > P2WI_MAX_FREQ) { | |
199 | dev_err(dev, | |
200 | "required clock-frequency (%u Hz) is too high (max = 6MHz)", | |
201 | clk_freq); | |
202 | return -EINVAL; | |
203 | } | |
204 | ||
205 | if (of_get_child_count(np) > 1) { | |
206 | dev_err(dev, "P2WI only supports one slave device\n"); | |
207 | return -EINVAL; | |
208 | } | |
209 | ||
210 | p2wi = devm_kzalloc(dev, sizeof(struct p2wi), GFP_KERNEL); | |
211 | if (!p2wi) | |
212 | return -ENOMEM; | |
213 | ||
214 | p2wi->slave_addr = -1; | |
215 | ||
216 | /* | |
217 | * Authorize a p2wi node without any children to be able to use an | |
218 | * i2c-dev from userpace. | |
219 | * In this case the slave_addr is set to -1 and won't be checked when | |
220 | * launching a P2WI transfer. | |
221 | */ | |
222 | childnp = of_get_next_available_child(np, NULL); | |
223 | if (childnp) { | |
224 | ret = of_property_read_u32(childnp, "reg", &slave_addr); | |
225 | if (ret) { | |
226 | dev_err(dev, "invalid slave address on node %s\n", | |
227 | childnp->full_name); | |
228 | return -EINVAL; | |
229 | } | |
230 | ||
231 | p2wi->slave_addr = slave_addr; | |
232 | } | |
233 | ||
234 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
235 | p2wi->regs = devm_ioremap_resource(dev, r); | |
236 | if (IS_ERR(p2wi->regs)) | |
237 | return PTR_ERR(p2wi->regs); | |
238 | ||
4632a93f | 239 | strlcpy(p2wi->adapter.name, pdev->name, sizeof(p2wi->adapter.name)); |
3e833490 BB |
240 | irq = platform_get_irq(pdev, 0); |
241 | if (irq < 0) { | |
c155ba88 | 242 | dev_err(dev, "failed to retrieve irq: %d\n", irq); |
3e833490 BB |
243 | return irq; |
244 | } | |
245 | ||
246 | p2wi->clk = devm_clk_get(dev, NULL); | |
247 | if (IS_ERR(p2wi->clk)) { | |
248 | ret = PTR_ERR(p2wi->clk); | |
249 | dev_err(dev, "failed to retrieve clk: %d\n", ret); | |
250 | return ret; | |
251 | } | |
252 | ||
253 | ret = clk_prepare_enable(p2wi->clk); | |
254 | if (ret) { | |
255 | dev_err(dev, "failed to enable clk: %d\n", ret); | |
256 | return ret; | |
257 | } | |
258 | ||
259 | parent_clk_freq = clk_get_rate(p2wi->clk); | |
260 | ||
261 | p2wi->rstc = devm_reset_control_get(dev, NULL); | |
262 | if (IS_ERR(p2wi->rstc)) { | |
263 | ret = PTR_ERR(p2wi->rstc); | |
264 | dev_err(dev, "failed to retrieve reset controller: %d\n", ret); | |
265 | goto err_clk_disable; | |
266 | } | |
267 | ||
268 | ret = reset_control_deassert(p2wi->rstc); | |
269 | if (ret) { | |
270 | dev_err(dev, "failed to deassert reset line: %d\n", ret); | |
271 | goto err_clk_disable; | |
272 | } | |
273 | ||
274 | init_completion(&p2wi->complete); | |
275 | p2wi->adapter.dev.parent = dev; | |
276 | p2wi->adapter.algo = &p2wi_algo; | |
277 | p2wi->adapter.owner = THIS_MODULE; | |
278 | p2wi->adapter.dev.of_node = pdev->dev.of_node; | |
279 | platform_set_drvdata(pdev, p2wi); | |
280 | i2c_set_adapdata(&p2wi->adapter, p2wi); | |
281 | ||
282 | ret = devm_request_irq(dev, irq, p2wi_interrupt, 0, pdev->name, p2wi); | |
283 | if (ret) { | |
284 | dev_err(dev, "can't register interrupt handler irq%d: %d\n", | |
285 | irq, ret); | |
286 | goto err_reset_assert; | |
287 | } | |
288 | ||
289 | writel(P2WI_CTRL_SOFT_RST, p2wi->regs + P2WI_CTRL); | |
290 | ||
291 | clk_div = parent_clk_freq / clk_freq; | |
292 | if (!clk_div) { | |
293 | dev_warn(dev, | |
294 | "clock-frequency is too high, setting it to %lu Hz\n", | |
295 | parent_clk_freq); | |
296 | clk_div = 1; | |
297 | } else if (clk_div > P2WI_CCR_MAX_CLK_DIV) { | |
298 | dev_warn(dev, | |
299 | "clock-frequency is too low, setting it to %lu Hz\n", | |
300 | parent_clk_freq / P2WI_CCR_MAX_CLK_DIV); | |
301 | clk_div = P2WI_CCR_MAX_CLK_DIV; | |
302 | } | |
303 | ||
304 | writel(P2WI_CCR_SDA_OUT_DELAY(1) | P2WI_CCR_CLK_DIV(clk_div), | |
305 | p2wi->regs + P2WI_CCR); | |
306 | ||
307 | ret = i2c_add_adapter(&p2wi->adapter); | |
308 | if (!ret) | |
309 | return 0; | |
310 | ||
311 | err_reset_assert: | |
312 | reset_control_assert(p2wi->rstc); | |
313 | ||
314 | err_clk_disable: | |
315 | clk_disable_unprepare(p2wi->clk); | |
316 | ||
317 | return ret; | |
318 | } | |
319 | ||
320 | static int p2wi_remove(struct platform_device *dev) | |
321 | { | |
322 | struct p2wi *p2wi = platform_get_drvdata(dev); | |
323 | ||
324 | reset_control_assert(p2wi->rstc); | |
325 | clk_disable_unprepare(p2wi->clk); | |
326 | i2c_del_adapter(&p2wi->adapter); | |
327 | ||
328 | return 0; | |
329 | } | |
330 | ||
331 | static struct platform_driver p2wi_driver = { | |
332 | .probe = p2wi_probe, | |
333 | .remove = p2wi_remove, | |
334 | .driver = { | |
3e833490 BB |
335 | .name = "i2c-sunxi-p2wi", |
336 | .of_match_table = p2wi_of_match_table, | |
337 | }, | |
338 | }; | |
339 | module_platform_driver(p2wi_driver); | |
340 | ||
341 | MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>"); | |
342 | MODULE_DESCRIPTION("Allwinner P2WI driver"); | |
343 | MODULE_LICENSE("GPL v2"); |