1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Driver for the ADB controller in the Mac I/O (Hydra) chip.
4 */
5#include <stdarg.h>
6#include <linux/types.h>
7#include <linux/errno.h>
8#include <linux/kernel.h>
9#include <linux/delay.h>
10#include <linux/spinlock.h>
11#include <linux/interrupt.h>
12#include <linux/pgtable.h>
13#include <asm/prom.h>
14#include <linux/adb.h>
15#include <asm/io.h>
16#include <asm/hydra.h>
17#include <asm/irq.h>
18#include <linux/init.h>
19#include <linux/ioport.h>
20
21struct preg {
22	unsigned char r;
23	char pad[15];
24};
25
26struct adb_regs {
27	struct preg intr;
28	struct preg data[9];
29	struct preg intr_enb;
30	struct preg dcount;
31	struct preg error;
32	struct preg ctrl;
33	struct preg autopoll;
34	struct preg active_hi;
35	struct preg active_lo;
36	struct preg test;
37};
38
39/* Bits in intr and intr_enb registers */
40#define DFB	1		/* data from bus */
41#define TAG	2		/* transfer access grant */
42
43/* Bits in dcount register */
44#define HMB	0x0f		/* how many bytes */
45#define APD	0x10		/* auto-poll data */
46
47/* Bits in error register */
48#define NRE	1		/* no response error */
49#define DLE	2		/* data lost error */
50
51/* Bits in ctrl register */
52#define TAR	1		/* transfer access request */
53#define DTB	2		/* data to bus */
54#define CRE	4		/* command response expected */
55#define ADB_RST	8		/* ADB reset */
56
57/* Bits in autopoll register */
58#define APE	1		/* autopoll enable */
59
60static volatile struct adb_regs __iomem *adb;
61static struct adb_request *current_req, *last_req;
62static DEFINE_SPINLOCK(macio_lock);
63
64static int macio_probe(void);
65static int macio_init(void);
66static irqreturn_t macio_adb_interrupt(int irq, void *arg);
67static int macio_send_request(struct adb_request *req, int sync);
68static int macio_adb_autopoll(int devs);
69static void macio_adb_poll(void);
70static int macio_adb_reset_bus(void);
71
72struct adb_driver macio_adb_driver = {
73	.name         = "MACIO",
74	.probe        = macio_probe,
75	.init         = macio_init,
76	.send_request = macio_send_request,
77	.autopoll     = macio_adb_autopoll,
78	.poll         = macio_adb_poll,
79	.reset_bus    = macio_adb_reset_bus,
80};
81
82int macio_probe(void)
83{
84	struct device_node *np;
85
86	np = of_find_compatible_node(NULL, "adb", "chrp,adb0");
87	if (np) {
88		of_node_put(np);
89		return 0;
90	}
91	return -ENODEV;
92}
93
94int macio_init(void)
95{
96	struct device_node *adbs;
97	struct resource r;
98	unsigned int irq;
99
100	adbs = of_find_compatible_node(NULL, "adb", "chrp,adb0");
101	if (adbs == 0)
102		return -ENXIO;
103
104	if (of_address_to_resource(adbs, 0, &r)) {
105		of_node_put(adbs);
106		return -ENXIO;
107	}
108	adb = ioremap(r.start, sizeof(struct adb_regs));
109	if (!adb) {
110		of_node_put(adbs);
111		return -ENOMEM;
112	}
113
114	out_8(&adb->ctrl.r, 0);
115	out_8(&adb->intr.r, 0);
116	out_8(&adb->error.r, 0);
117	out_8(&adb->active_hi.r, 0xff); /* for now, set all devices active */
118	out_8(&adb->active_lo.r, 0xff);
119	out_8(&adb->autopoll.r, APE);
120
121	irq = irq_of_parse_and_map(adbs, 0);
122	of_node_put(adbs);
123	if (request_irq(irq, macio_adb_interrupt, 0, "ADB", (void *)0)) {
124		printk(KERN_ERR "ADB: can't get irq %d\n", irq);
125		return -EAGAIN;
126	}
127	out_8(&adb->intr_enb.r, DFB | TAG);
128
129	printk("adb: mac-io driver 1.0 for unified ADB\n");
130
131	return 0;
132}
133
134static int macio_adb_autopoll(int devs)
135{
136	unsigned long flags;
137
138	spin_lock_irqsave(&macio_lock, flags);
139	out_8(&adb->active_hi.r, devs >> 8);
140	out_8(&adb->active_lo.r, devs);
141	out_8(&adb->autopoll.r, devs? APE: 0);
142	spin_unlock_irqrestore(&macio_lock, flags);
143	return 0;
144}
145
146static int macio_adb_reset_bus(void)
147{
148	unsigned long flags;
149	int timeout = 1000000;
150
151	/* Hrm... we may want to not lock interrupts for so
152	 * long ... oh well, who uses that chip anyway ? :)
153	 * That function will be seldom used during boot
154	 * on rare machines, so...
155	 */
156	spin_lock_irqsave(&macio_lock, flags);
157	out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | ADB_RST);
158	while ((in_8(&adb->ctrl.r) & ADB_RST) != 0) {
159		if (--timeout == 0) {
160			out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) & ~ADB_RST);
161			spin_unlock_irqrestore(&macio_lock, flags);
162			return -1;
163		}
164	}
165	spin_unlock_irqrestore(&macio_lock, flags);
166	return 0;
167}
168
169/* Send an ADB command */
170static int macio_send_request(struct adb_request *req, int sync)
171{
172	unsigned long flags;
173	int i;
174
175	if (req->data[0] != ADB_PACKET)
176		return -EINVAL;
177
178	for (i = 0; i < req->nbytes - 1; ++i)
179		req->data[i] = req->data[i+1];
180	--req->nbytes;
181
182	req->next = NULL;
183	req->sent = 0;
184	req->complete = 0;
185	req->reply_len = 0;
186
187	spin_lock_irqsave(&macio_lock, flags);
188	if (current_req != 0) {
189		last_req->next = req;
190		last_req = req;
191	} else {
192		current_req = last_req = req;
193		out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
194	}
195	spin_unlock_irqrestore(&macio_lock, flags);
196
197	if (sync) {
198		while (!req->complete)
199			macio_adb_poll();
200	}
201
202	return 0;
203}
204
205static irqreturn_t macio_adb_interrupt(int irq, void *arg)
206{
207	int i, n, err;
208	struct adb_request *req = NULL;
209	unsigned char ibuf[16];
210	int ibuf_len = 0;
211	int complete = 0;
212	int autopoll = 0;
213	int handled = 0;
214
215	spin_lock(&macio_lock);
216	if (in_8(&adb->intr.r) & TAG) {
217		handled = 1;
218		if ((req = current_req) != 0) {
219			/* put the current request in */
220			for (i = 0; i < req->nbytes; ++i)
221				out_8(&adb->data[i].r, req->data[i]);
222			out_8(&adb->dcount.r, req->nbytes & HMB);
223			req->sent = 1;
224			if (req->reply_expected) {
225				out_8(&adb->ctrl.r, DTB + CRE);
226			} else {
227				out_8(&adb->ctrl.r, DTB);
228				current_req = req->next;
229				complete = 1;
230				if (current_req)
231					out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
232			}
233		}
234		out_8(&adb->intr.r, 0);
235	}
236
237	if (in_8(&adb->intr.r) & DFB) {
238		handled = 1;
239		err = in_8(&adb->error.r);
240		if (current_req && current_req->sent) {
241			/* this is the response to a command */
242			req = current_req;
243			if (err == 0) {
244				req->reply_len = in_8(&adb->dcount.r) & HMB;
245				for (i = 0; i < req->reply_len; ++i)
246					req->reply[i] = in_8(&adb->data[i].r);
247			}
248			current_req = req->next;
249			complete = 1;
250			if (current_req)
251				out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
252		} else if (err == 0) {
253			/* autopoll data */
254			n = in_8(&adb->dcount.r) & HMB;
255			for (i = 0; i < n; ++i)
256				ibuf[i] = in_8(&adb->data[i].r);
257			ibuf_len = n;
258			autopoll = (in_8(&adb->dcount.r) & APD) != 0;
259		}
260		out_8(&adb->error.r, 0);
261		out_8(&adb->intr.r, 0);
262	}
263	spin_unlock(&macio_lock);
264	if (complete && req) {
265	    void (*done)(struct adb_request *) = req->done;
266	    mb();
267	    req->complete = 1;
268	    /* Here, we assume that if the request has a done member, the
269    	     * struct request will survive to setting req->complete to 1
270	     */
271	    if (done)
272		(*done)(req);
273	}
274	if (ibuf_len)
275		adb_input(ibuf, ibuf_len, autopoll);
276
277	return IRQ_RETVAL(handled);
278}
279
280static void macio_adb_poll(void)
281{
282	unsigned long flags;
283
284	local_irq_save(flags);
285	if (in_8(&adb->intr.r) != 0)
286		macio_adb_interrupt(0, NULL);
287	local_irq_restore(flags);
288}
289