xref: /openbmc/linux/drivers/nfc/st-nci/spi.c (revision a0386bba)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * SPI Link Layer for ST NCI based Driver
4  * Copyright (C) 2014-2015 STMicroelectronics SAS. All rights reserved.
5  */
6 
7 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
8 
9 #include <linux/module.h>
10 #include <linux/spi/spi.h>
11 #include <linux/gpio/consumer.h>
12 #include <linux/acpi.h>
13 #include <linux/interrupt.h>
14 #include <linux/delay.h>
15 #include <linux/nfc.h>
16 #include <linux/of.h>
17 #include <net/nfc/nci.h>
18 
19 #include "st-nci.h"
20 
21 #define DRIVER_DESC "NCI NFC driver for ST_NCI"
22 
23 /* ndlc header */
24 #define ST_NCI_FRAME_HEADROOM	1
25 #define ST_NCI_FRAME_TAILROOM	0
26 
27 #define ST_NCI_SPI_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
28 #define ST_NCI_SPI_MAX_SIZE 250 /* req 4.2.1 */
29 
30 #define ST_NCI_DRIVER_NAME "st_nci"
31 #define ST_NCI_SPI_DRIVER_NAME "st_nci_spi"
32 
33 struct st_nci_spi_phy {
34 	struct spi_device *spi_dev;
35 	struct llt_ndlc *ndlc;
36 
37 	bool irq_active;
38 
39 	struct gpio_desc *gpiod_reset;
40 
41 	struct st_nci_se_status se_status;
42 };
43 
st_nci_spi_enable(void * phy_id)44 static int st_nci_spi_enable(void *phy_id)
45 {
46 	struct st_nci_spi_phy *phy = phy_id;
47 
48 	gpiod_set_value(phy->gpiod_reset, 0);
49 	usleep_range(10000, 15000);
50 	gpiod_set_value(phy->gpiod_reset, 1);
51 	usleep_range(80000, 85000);
52 
53 	if (phy->ndlc->powered == 0 && phy->irq_active == 0) {
54 		enable_irq(phy->spi_dev->irq);
55 		phy->irq_active = true;
56 	}
57 
58 	return 0;
59 }
60 
st_nci_spi_disable(void * phy_id)61 static void st_nci_spi_disable(void *phy_id)
62 {
63 	struct st_nci_spi_phy *phy = phy_id;
64 
65 	disable_irq_nosync(phy->spi_dev->irq);
66 	phy->irq_active = false;
67 }
68 
69 /*
70  * Writing a frame must not return the number of written bytes.
71  * It must return either zero for success, or <0 for error.
72  * In addition, it must not alter the skb
73  */
st_nci_spi_write(void * phy_id,struct sk_buff * skb)74 static int st_nci_spi_write(void *phy_id, struct sk_buff *skb)
75 {
76 	int r;
77 	struct st_nci_spi_phy *phy = phy_id;
78 	struct spi_device *dev = phy->spi_dev;
79 	struct sk_buff *skb_rx;
80 	u8 buf[ST_NCI_SPI_MAX_SIZE + NCI_DATA_HDR_SIZE +
81 	       ST_NCI_FRAME_HEADROOM + ST_NCI_FRAME_TAILROOM];
82 	struct spi_transfer spi_xfer = {
83 		.tx_buf = skb->data,
84 		.rx_buf = buf,
85 		.len = skb->len,
86 	};
87 
88 	if (phy->ndlc->hard_fault != 0)
89 		return phy->ndlc->hard_fault;
90 
91 	r = spi_sync_transfer(dev, &spi_xfer, 1);
92 	/*
93 	 * We may have received some valuable data on miso line.
94 	 * Send them back in the ndlc state machine.
95 	 */
96 	if (!r) {
97 		skb_rx = alloc_skb(skb->len, GFP_KERNEL);
98 		if (!skb_rx)
99 			return -ENOMEM;
100 
101 		skb_put(skb_rx, skb->len);
102 		memcpy(skb_rx->data, buf, skb->len);
103 		ndlc_recv(phy->ndlc, skb_rx);
104 	}
105 
106 	return r;
107 }
108 
109 /*
110  * Reads an ndlc frame and returns it in a newly allocated sk_buff.
111  * returns:
112  * 0 : if received frame is complete
113  * -EREMOTEIO : i2c read error (fatal)
114  * -EBADMSG : frame was incorrect and discarded
115  * -ENOMEM : cannot allocate skb, frame dropped
116  */
st_nci_spi_read(struct st_nci_spi_phy * phy,struct sk_buff ** skb)117 static int st_nci_spi_read(struct st_nci_spi_phy *phy,
118 			struct sk_buff **skb)
119 {
120 	int r;
121 	u8 len;
122 	u8 buf[ST_NCI_SPI_MAX_SIZE];
123 	struct spi_device *dev = phy->spi_dev;
124 	struct spi_transfer spi_xfer = {
125 		.rx_buf = buf,
126 		.len = ST_NCI_SPI_MIN_SIZE,
127 	};
128 
129 	r = spi_sync_transfer(dev, &spi_xfer, 1);
130 	if (r < 0)
131 		return -EREMOTEIO;
132 
133 	len = be16_to_cpu(*(__be16 *) (buf + 2));
134 	if (len > ST_NCI_SPI_MAX_SIZE) {
135 		nfc_err(&dev->dev, "invalid frame len\n");
136 		phy->ndlc->hard_fault = 1;
137 		return -EBADMSG;
138 	}
139 
140 	*skb = alloc_skb(ST_NCI_SPI_MIN_SIZE + len, GFP_KERNEL);
141 	if (*skb == NULL)
142 		return -ENOMEM;
143 
144 	skb_reserve(*skb, ST_NCI_SPI_MIN_SIZE);
145 	skb_put(*skb, ST_NCI_SPI_MIN_SIZE);
146 	memcpy((*skb)->data, buf, ST_NCI_SPI_MIN_SIZE);
147 
148 	if (!len)
149 		return 0;
150 
151 	spi_xfer.len = len;
152 	r = spi_sync_transfer(dev, &spi_xfer, 1);
153 	if (r < 0) {
154 		kfree_skb(*skb);
155 		return -EREMOTEIO;
156 	}
157 
158 	skb_put(*skb, len);
159 	memcpy((*skb)->data + ST_NCI_SPI_MIN_SIZE, buf, len);
160 
161 	return 0;
162 }
163 
164 /*
165  * Reads an ndlc frame from the chip.
166  *
167  * On ST21NFCB, IRQ goes in idle state when read starts.
168  */
st_nci_irq_thread_fn(int irq,void * phy_id)169 static irqreturn_t st_nci_irq_thread_fn(int irq, void *phy_id)
170 {
171 	struct st_nci_spi_phy *phy = phy_id;
172 	struct sk_buff *skb = NULL;
173 	int r;
174 
175 	if (!phy || !phy->ndlc || irq != phy->spi_dev->irq) {
176 		WARN_ON_ONCE(1);
177 		return IRQ_NONE;
178 	}
179 
180 	if (phy->ndlc->hard_fault)
181 		return IRQ_HANDLED;
182 
183 	if (!phy->ndlc->powered) {
184 		st_nci_spi_disable(phy);
185 		return IRQ_HANDLED;
186 	}
187 
188 	r = st_nci_spi_read(phy, &skb);
189 	if (r == -EREMOTEIO || r == -ENOMEM || r == -EBADMSG)
190 		return IRQ_HANDLED;
191 
192 	ndlc_recv(phy->ndlc, skb);
193 
194 	return IRQ_HANDLED;
195 }
196 
197 static const struct nfc_phy_ops spi_phy_ops = {
198 	.write = st_nci_spi_write,
199 	.enable = st_nci_spi_enable,
200 	.disable = st_nci_spi_disable,
201 };
202 
203 static const struct acpi_gpio_params reset_gpios = { 1, 0, false };
204 
205 static const struct acpi_gpio_mapping acpi_st_nci_gpios[] = {
206 	{ "reset-gpios", &reset_gpios, 1 },
207 	{},
208 };
209 
st_nci_spi_probe(struct spi_device * dev)210 static int st_nci_spi_probe(struct spi_device *dev)
211 {
212 	struct st_nci_spi_phy *phy;
213 	int r;
214 
215 	/* Check SPI platform functionnalities */
216 	if (!dev) {
217 		pr_debug("%s: dev is NULL. Device is not accessible.\n",
218 			__func__);
219 		return -ENODEV;
220 	}
221 
222 	phy = devm_kzalloc(&dev->dev, sizeof(struct st_nci_spi_phy),
223 			   GFP_KERNEL);
224 	if (!phy)
225 		return -ENOMEM;
226 
227 	phy->spi_dev = dev;
228 
229 	spi_set_drvdata(dev, phy);
230 
231 	r = devm_acpi_dev_add_driver_gpios(&dev->dev, acpi_st_nci_gpios);
232 	if (r)
233 		dev_dbg(&dev->dev, "Unable to add GPIO mapping table\n");
234 
235 	/* Get RESET GPIO */
236 	phy->gpiod_reset = devm_gpiod_get(&dev->dev, "reset", GPIOD_OUT_HIGH);
237 	if (IS_ERR(phy->gpiod_reset)) {
238 		nfc_err(&dev->dev, "Unable to get RESET GPIO\n");
239 		return PTR_ERR(phy->gpiod_reset);
240 	}
241 
242 	phy->se_status.is_ese_present =
243 			device_property_read_bool(&dev->dev, "ese-present");
244 	phy->se_status.is_uicc_present =
245 			device_property_read_bool(&dev->dev, "uicc-present");
246 
247 	r = ndlc_probe(phy, &spi_phy_ops, &dev->dev,
248 			ST_NCI_FRAME_HEADROOM, ST_NCI_FRAME_TAILROOM,
249 			&phy->ndlc, &phy->se_status);
250 	if (r < 0) {
251 		nfc_err(&dev->dev, "Unable to register ndlc layer\n");
252 		return r;
253 	}
254 
255 	phy->irq_active = true;
256 	r = devm_request_threaded_irq(&dev->dev, dev->irq, NULL,
257 				st_nci_irq_thread_fn,
258 				IRQF_ONESHOT,
259 				ST_NCI_SPI_DRIVER_NAME, phy);
260 	if (r < 0)
261 		nfc_err(&dev->dev, "Unable to register IRQ handler\n");
262 
263 	return r;
264 }
265 
st_nci_spi_remove(struct spi_device * dev)266 static void st_nci_spi_remove(struct spi_device *dev)
267 {
268 	struct st_nci_spi_phy *phy = spi_get_drvdata(dev);
269 
270 	ndlc_remove(phy->ndlc);
271 }
272 
273 static struct spi_device_id st_nci_spi_id_table[] = {
274 	{ST_NCI_SPI_DRIVER_NAME, 0},
275 	{"st21nfcb-spi", 0},
276 	{}
277 };
278 MODULE_DEVICE_TABLE(spi, st_nci_spi_id_table);
279 
280 static const struct acpi_device_id st_nci_spi_acpi_match[] __maybe_unused = {
281 	{"SMO2101", 0},
282 	{}
283 };
284 MODULE_DEVICE_TABLE(acpi, st_nci_spi_acpi_match);
285 
286 static const struct of_device_id of_st_nci_spi_match[] __maybe_unused = {
287 	{ .compatible = "st,st21nfcb-spi", },
288 	{}
289 };
290 MODULE_DEVICE_TABLE(of, of_st_nci_spi_match);
291 
292 static struct spi_driver st_nci_spi_driver = {
293 	.driver = {
294 		.name = ST_NCI_SPI_DRIVER_NAME,
295 		.of_match_table = of_match_ptr(of_st_nci_spi_match),
296 		.acpi_match_table = ACPI_PTR(st_nci_spi_acpi_match),
297 	},
298 	.probe = st_nci_spi_probe,
299 	.id_table = st_nci_spi_id_table,
300 	.remove = st_nci_spi_remove,
301 };
302 module_spi_driver(st_nci_spi_driver);
303 
304 MODULE_LICENSE("GPL");
305 MODULE_DESCRIPTION(DRIVER_DESC);
306