xref: /openbmc/linux/drivers/mfd/rsmu_spi.c (revision ee65728e)
1  // SPDX-License-Identifier: GPL-2.0+
2  /*
3   * SPI driver for Renesas Synchronization Management Unit (SMU) devices.
4   *
5   * Copyright (C) 2021 Integrated Device Technology, Inc., a Renesas Company.
6   */
7  
8  #include <linux/init.h>
9  #include <linux/kernel.h>
10  #include <linux/mfd/core.h>
11  #include <linux/mfd/rsmu.h>
12  #include <linux/module.h>
13  #include <linux/of.h>
14  #include <linux/regmap.h>
15  #include <linux/slab.h>
16  #include <linux/spi/spi.h>
17  
18  #include "rsmu.h"
19  
20  #define	RSMU_CM_PAGE_ADDR		0x7C
21  #define	RSMU_SABRE_PAGE_ADDR		0x7F
22  #define	RSMU_HIGHER_ADDR_MASK		0xFF80
23  #define	RSMU_HIGHER_ADDR_SHIFT		7
24  #define	RSMU_LOWER_ADDR_MASK		0x7F
25  
26  static int rsmu_read_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes)
27  {
28  	struct spi_device *client = to_spi_device(rsmu->dev);
29  	struct spi_transfer xfer = {0};
30  	struct spi_message msg;
31  	u8 cmd[256] = {0};
32  	u8 rsp[256] = {0};
33  	int ret;
34  
35  	cmd[0] = reg | 0x80;
36  	xfer.rx_buf = rsp;
37  	xfer.len = bytes + 1;
38  	xfer.tx_buf = cmd;
39  	xfer.bits_per_word = client->bits_per_word;
40  	xfer.speed_hz = client->max_speed_hz;
41  
42  	spi_message_init(&msg);
43  	spi_message_add_tail(&xfer, &msg);
44  
45  	/*
46  	 * 4-wire SPI is a shift register, so for every byte you send,
47  	 * you get one back at the same time. Example read from 0xC024,
48  	 * which has value of 0x2D
49  	 *
50  	 * MOSI:
51  	 *       7C 00 C0 #Set page register
52  	 *       A4 00    #MSB is set, so this is read command
53  	 * MISO:
54  	 *       XX 2D    #XX is a dummy byte from sending A4 and we
55  	 *                 need to throw it away
56  	 */
57  	ret = spi_sync(client, &msg);
58  	if (ret >= 0)
59  		memcpy(buf, &rsp[1], xfer.len-1);
60  
61  	return ret;
62  }
63  
64  static int rsmu_write_device(struct rsmu_ddata *rsmu, u8 reg, u8 *buf, u16 bytes)
65  {
66  	struct spi_device *client = to_spi_device(rsmu->dev);
67  	struct spi_transfer xfer = {0};
68  	struct spi_message msg;
69  	u8 cmd[256] = {0};
70  
71  	cmd[0] = reg;
72  	memcpy(&cmd[1], buf, bytes);
73  
74  	xfer.len = bytes + 1;
75  	xfer.tx_buf = cmd;
76  	xfer.bits_per_word = client->bits_per_word;
77  	xfer.speed_hz = client->max_speed_hz;
78  	spi_message_init(&msg);
79  	spi_message_add_tail(&xfer, &msg);
80  
81  	return  spi_sync(client, &msg);
82  }
83  
84  /*
85   * 1-byte (1B) offset addressing:
86   * 16-bit register address: the lower 7 bits of the register address come
87   * from the offset addr byte and the upper 9 bits come from the page register.
88   */
89  static int rsmu_write_page_register(struct rsmu_ddata *rsmu, u16 reg)
90  {
91  	u8 page_reg;
92  	u8 buf[2];
93  	u16 bytes;
94  	u16 page;
95  	int err;
96  
97  	switch (rsmu->type) {
98  	case RSMU_CM:
99  		page_reg = RSMU_CM_PAGE_ADDR;
100  		page = reg & RSMU_HIGHER_ADDR_MASK;
101  		buf[0] = (u8)(page & 0xff);
102  		buf[1] = (u8)((page >> 8) & 0xff);
103  		bytes = 2;
104  		break;
105  	case RSMU_SABRE:
106  		page_reg = RSMU_SABRE_PAGE_ADDR;
107  		page = reg >> RSMU_HIGHER_ADDR_SHIFT;
108  		buf[0] = (u8)(page & 0xff);
109  		bytes = 1;
110  		break;
111  	default:
112  		dev_err(rsmu->dev, "Unsupported RSMU device type: %d\n", rsmu->type);
113  		return -ENODEV;
114  	}
115  
116  	/* Simply return if we are on the same page */
117  	if (rsmu->page == page)
118  		return 0;
119  
120  	err = rsmu_write_device(rsmu, page_reg, buf, bytes);
121  	if (err)
122  		dev_err(rsmu->dev, "Failed to set page offset 0x%x\n", page);
123  	else
124  		/* Remember the last page */
125  		rsmu->page = page;
126  
127  	return err;
128  }
129  
130  static int rsmu_reg_read(void *context, unsigned int reg, unsigned int *val)
131  {
132  	struct rsmu_ddata *rsmu = spi_get_drvdata((struct spi_device *)context);
133  	u8 addr = (u8)(reg & RSMU_LOWER_ADDR_MASK);
134  	int err;
135  
136  	err = rsmu_write_page_register(rsmu, reg);
137  	if (err)
138  		return err;
139  
140  	err = rsmu_read_device(rsmu, addr, (u8 *)val, 1);
141  	if (err)
142  		dev_err(rsmu->dev, "Failed to read offset address 0x%x\n", addr);
143  
144  	return err;
145  }
146  
147  static int rsmu_reg_write(void *context, unsigned int reg, unsigned int val)
148  {
149  	struct rsmu_ddata *rsmu = spi_get_drvdata((struct spi_device *)context);
150  	u8 addr = (u8)(reg & RSMU_LOWER_ADDR_MASK);
151  	u8 data = (u8)val;
152  	int err;
153  
154  	err = rsmu_write_page_register(rsmu, reg);
155  	if (err)
156  		return err;
157  
158  	err = rsmu_write_device(rsmu, addr, &data, 1);
159  	if (err)
160  		dev_err(rsmu->dev,
161  			"Failed to write offset address 0x%x\n", addr);
162  
163  	return err;
164  }
165  
166  static const struct regmap_config rsmu_cm_regmap_config = {
167  	.reg_bits = 16,
168  	.val_bits = 8,
169  	.max_register = 0xD000,
170  	.reg_read = rsmu_reg_read,
171  	.reg_write = rsmu_reg_write,
172  	.cache_type = REGCACHE_NONE,
173  };
174  
175  static const struct regmap_config rsmu_sabre_regmap_config = {
176  	.reg_bits = 16,
177  	.val_bits = 8,
178  	.max_register = 0x400,
179  	.reg_read = rsmu_reg_read,
180  	.reg_write = rsmu_reg_write,
181  	.cache_type = REGCACHE_NONE,
182  };
183  
184  static int rsmu_spi_probe(struct spi_device *client)
185  {
186  	const struct spi_device_id *id = spi_get_device_id(client);
187  	const struct regmap_config *cfg;
188  	struct rsmu_ddata *rsmu;
189  	int ret;
190  
191  	rsmu = devm_kzalloc(&client->dev, sizeof(*rsmu), GFP_KERNEL);
192  	if (!rsmu)
193  		return -ENOMEM;
194  
195  	spi_set_drvdata(client, rsmu);
196  
197  	rsmu->dev = &client->dev;
198  	rsmu->type = (enum rsmu_type)id->driver_data;
199  
200  	/* Initialize regmap */
201  	switch (rsmu->type) {
202  	case RSMU_CM:
203  		cfg = &rsmu_cm_regmap_config;
204  		break;
205  	case RSMU_SABRE:
206  		cfg = &rsmu_sabre_regmap_config;
207  		break;
208  	default:
209  		dev_err(rsmu->dev, "Unsupported RSMU device type: %d\n", rsmu->type);
210  		return -ENODEV;
211  	}
212  
213  	rsmu->regmap = devm_regmap_init(&client->dev, NULL, client, cfg);
214  	if (IS_ERR(rsmu->regmap)) {
215  		ret = PTR_ERR(rsmu->regmap);
216  		dev_err(rsmu->dev, "Failed to allocate register map: %d\n", ret);
217  		return ret;
218  	}
219  
220  	return rsmu_core_init(rsmu);
221  }
222  
223  static void rsmu_spi_remove(struct spi_device *client)
224  {
225  	struct rsmu_ddata *rsmu = spi_get_drvdata(client);
226  
227  	rsmu_core_exit(rsmu);
228  }
229  
230  static const struct spi_device_id rsmu_spi_id[] = {
231  	{ "8a34000",  RSMU_CM },
232  	{ "8a34001",  RSMU_CM },
233  	{ "82p33810", RSMU_SABRE },
234  	{ "82p33811", RSMU_SABRE },
235  	{}
236  };
237  MODULE_DEVICE_TABLE(spi, rsmu_spi_id);
238  
239  static const struct of_device_id rsmu_spi_of_match[] = {
240  	{ .compatible = "idt,8a34000",  .data = (void *)RSMU_CM },
241  	{ .compatible = "idt,8a34001",  .data = (void *)RSMU_CM },
242  	{ .compatible = "idt,82p33810", .data = (void *)RSMU_SABRE },
243  	{ .compatible = "idt,82p33811", .data = (void *)RSMU_SABRE },
244  	{}
245  };
246  MODULE_DEVICE_TABLE(of, rsmu_spi_of_match);
247  
248  static struct spi_driver rsmu_spi_driver = {
249  	.driver = {
250  		.name = "rsmu-spi",
251  		.of_match_table = of_match_ptr(rsmu_spi_of_match),
252  	},
253  	.probe = rsmu_spi_probe,
254  	.remove	= rsmu_spi_remove,
255  	.id_table = rsmu_spi_id,
256  };
257  
258  static int __init rsmu_spi_init(void)
259  {
260  	return spi_register_driver(&rsmu_spi_driver);
261  }
262  subsys_initcall(rsmu_spi_init);
263  
264  static void __exit rsmu_spi_exit(void)
265  {
266  	spi_unregister_driver(&rsmu_spi_driver);
267  }
268  module_exit(rsmu_spi_exit);
269  
270  MODULE_DESCRIPTION("Renesas SMU SPI driver");
271  MODULE_LICENSE("GPL");
272