1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  Copyright © 2008 Ilya Yanok, Emcraft Systems
4  */
5 
6 #include <linux/slab.h>
7 #include <linux/module.h>
8 #include <linux/mtd/mtd.h>
9 #include <linux/mtd/rawnand.h>
10 #include <linux/mtd/partitions.h>
11 #include <linux/of.h>
12 #include <linux/of_address.h>
13 #include <linux/platform_device.h>
14 #include <linux/io.h>
15 
16 #define FPGA_NAND_CMD_MASK		(0x7 << 28)
17 #define FPGA_NAND_CMD_COMMAND		(0x0 << 28)
18 #define FPGA_NAND_CMD_ADDR		(0x1 << 28)
19 #define FPGA_NAND_CMD_READ		(0x2 << 28)
20 #define FPGA_NAND_CMD_WRITE		(0x3 << 28)
21 #define FPGA_NAND_BUSY			(0x1 << 15)
22 #define FPGA_NAND_ENABLE		(0x1 << 31)
23 #define FPGA_NAND_DATA_SHIFT		16
24 
25 struct socrates_nand_host {
26 	struct nand_controller	controller;
27 	struct nand_chip	nand_chip;
28 	void __iomem		*io_base;
29 	struct device		*dev;
30 };
31 
32 /**
33  * socrates_nand_write_buf -  write buffer to chip
34  * @this:	NAND chip object
35  * @buf:	data buffer
36  * @len:	number of bytes to write
37  */
38 static void socrates_nand_write_buf(struct nand_chip *this, const uint8_t *buf,
39 				    int len)
40 {
41 	int i;
42 	struct socrates_nand_host *host = nand_get_controller_data(this);
43 
44 	for (i = 0; i < len; i++) {
45 		out_be32(host->io_base, FPGA_NAND_ENABLE |
46 				FPGA_NAND_CMD_WRITE |
47 				(buf[i] << FPGA_NAND_DATA_SHIFT));
48 	}
49 }
50 
51 /**
52  * socrates_nand_read_buf -  read chip data into buffer
53  * @this:	NAND chip object
54  * @buf:	buffer to store date
55  * @len:	number of bytes to read
56  */
57 static void socrates_nand_read_buf(struct nand_chip *this, uint8_t *buf,
58 				   int len)
59 {
60 	int i;
61 	struct socrates_nand_host *host = nand_get_controller_data(this);
62 	uint32_t val;
63 
64 	val = FPGA_NAND_ENABLE | FPGA_NAND_CMD_READ;
65 
66 	out_be32(host->io_base, val);
67 	for (i = 0; i < len; i++) {
68 		buf[i] = (in_be32(host->io_base) >>
69 				FPGA_NAND_DATA_SHIFT) & 0xff;
70 	}
71 }
72 
73 /**
74  * socrates_nand_read_byte -  read one byte from the chip
75  * @mtd:	MTD device structure
76  */
77 static uint8_t socrates_nand_read_byte(struct nand_chip *this)
78 {
79 	uint8_t byte;
80 	socrates_nand_read_buf(this, &byte, sizeof(byte));
81 	return byte;
82 }
83 
84 /*
85  * Hardware specific access to control-lines
86  */
87 static void socrates_nand_cmd_ctrl(struct nand_chip *nand_chip, int cmd,
88 				   unsigned int ctrl)
89 {
90 	struct socrates_nand_host *host = nand_get_controller_data(nand_chip);
91 	uint32_t val;
92 
93 	if (cmd == NAND_CMD_NONE)
94 		return;
95 
96 	if (ctrl & NAND_CLE)
97 		val = FPGA_NAND_CMD_COMMAND;
98 	else
99 		val = FPGA_NAND_CMD_ADDR;
100 
101 	if (ctrl & NAND_NCE)
102 		val |= FPGA_NAND_ENABLE;
103 
104 	val |= (cmd & 0xff) << FPGA_NAND_DATA_SHIFT;
105 
106 	out_be32(host->io_base, val);
107 }
108 
109 /*
110  * Read the Device Ready pin.
111  */
112 static int socrates_nand_device_ready(struct nand_chip *nand_chip)
113 {
114 	struct socrates_nand_host *host = nand_get_controller_data(nand_chip);
115 
116 	if (in_be32(host->io_base) & FPGA_NAND_BUSY)
117 		return 0; /* busy */
118 	return 1;
119 }
120 
121 static int socrates_attach_chip(struct nand_chip *chip)
122 {
123 	if (chip->ecc.engine_type == NAND_ECC_ENGINE_TYPE_SOFT &&
124 	    chip->ecc.algo == NAND_ECC_ALGO_UNKNOWN)
125 		chip->ecc.algo = NAND_ECC_ALGO_HAMMING;
126 
127 	return 0;
128 }
129 
130 static const struct nand_controller_ops socrates_ops = {
131 	.attach_chip = socrates_attach_chip,
132 };
133 
134 /*
135  * Probe for the NAND device.
136  */
137 static int socrates_nand_probe(struct platform_device *ofdev)
138 {
139 	struct socrates_nand_host *host;
140 	struct mtd_info *mtd;
141 	struct nand_chip *nand_chip;
142 	int res;
143 
144 	/* Allocate memory for the device structure (and zero it) */
145 	host = devm_kzalloc(&ofdev->dev, sizeof(*host), GFP_KERNEL);
146 	if (!host)
147 		return -ENOMEM;
148 
149 	host->io_base = of_iomap(ofdev->dev.of_node, 0);
150 	if (host->io_base == NULL) {
151 		dev_err(&ofdev->dev, "ioremap failed\n");
152 		return -EIO;
153 	}
154 
155 	nand_chip = &host->nand_chip;
156 	mtd = nand_to_mtd(nand_chip);
157 	host->dev = &ofdev->dev;
158 
159 	nand_controller_init(&host->controller);
160 	host->controller.ops = &socrates_ops;
161 	nand_chip->controller = &host->controller;
162 
163 	/* link the private data structures */
164 	nand_set_controller_data(nand_chip, host);
165 	nand_set_flash_node(nand_chip, ofdev->dev.of_node);
166 	mtd->name = "socrates_nand";
167 	mtd->dev.parent = &ofdev->dev;
168 
169 	nand_chip->legacy.cmd_ctrl = socrates_nand_cmd_ctrl;
170 	nand_chip->legacy.read_byte = socrates_nand_read_byte;
171 	nand_chip->legacy.write_buf = socrates_nand_write_buf;
172 	nand_chip->legacy.read_buf = socrates_nand_read_buf;
173 	nand_chip->legacy.dev_ready = socrates_nand_device_ready;
174 
175 	/* TODO: I have no idea what real delay is. */
176 	nand_chip->legacy.chip_delay = 20;	/* 20us command delay time */
177 
178 	/*
179 	 * This driver assumes that the default ECC engine should be TYPE_SOFT.
180 	 * Set ->engine_type before registering the NAND devices in order to
181 	 * provide a driver specific default value.
182 	 */
183 	nand_chip->ecc.engine_type = NAND_ECC_ENGINE_TYPE_SOFT;
184 
185 	dev_set_drvdata(&ofdev->dev, host);
186 
187 	res = nand_scan(nand_chip, 1);
188 	if (res)
189 		goto out;
190 
191 	res = mtd_device_register(mtd, NULL, 0);
192 	if (!res)
193 		return res;
194 
195 	nand_cleanup(nand_chip);
196 
197 out:
198 	iounmap(host->io_base);
199 	return res;
200 }
201 
202 /*
203  * Remove a NAND device.
204  */
205 static void socrates_nand_remove(struct platform_device *ofdev)
206 {
207 	struct socrates_nand_host *host = dev_get_drvdata(&ofdev->dev);
208 	struct nand_chip *chip = &host->nand_chip;
209 	int ret;
210 
211 	ret = mtd_device_unregister(nand_to_mtd(chip));
212 	WARN_ON(ret);
213 	nand_cleanup(chip);
214 
215 	iounmap(host->io_base);
216 }
217 
218 static const struct of_device_id socrates_nand_match[] =
219 {
220 	{
221 		.compatible   = "abb,socrates-nand",
222 	},
223 	{},
224 };
225 
226 MODULE_DEVICE_TABLE(of, socrates_nand_match);
227 
228 static struct platform_driver socrates_nand_driver = {
229 	.driver = {
230 		.name = "socrates_nand",
231 		.of_match_table = socrates_nand_match,
232 	},
233 	.probe		= socrates_nand_probe,
234 	.remove_new	= socrates_nand_remove,
235 };
236 
237 module_platform_driver(socrates_nand_driver);
238 
239 MODULE_LICENSE("GPL");
240 MODULE_AUTHOR("Ilya Yanok");
241 MODULE_DESCRIPTION("NAND driver for Socrates board");
242