1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Driver for the ADB controller in the Mac I/O (Hydra) chip.
4 */
5#include <linux/types.h>
6#include <linux/errno.h>
7#include <linux/kernel.h>
8#include <linux/delay.h>
9#include <linux/spinlock.h>
10#include <linux/interrupt.h>
11#include <linux/pgtable.h>
12#include <linux/of.h>
13#include <linux/of_address.h>
14#include <linux/of_irq.h>
15#include <linux/adb.h>
16
17#include <asm/io.h>
18#include <asm/hydra.h>
19#include <asm/irq.h>
20#include <linux/init.h>
21#include <linux/ioport.h>
22
23struct preg {
24	unsigned char r;
25	char pad[15];
26};
27
28struct adb_regs {
29	struct preg intr;
30	struct preg data[9];
31	struct preg intr_enb;
32	struct preg dcount;
33	struct preg error;
34	struct preg ctrl;
35	struct preg autopoll;
36	struct preg active_hi;
37	struct preg active_lo;
38	struct preg test;
39};
40
41/* Bits in intr and intr_enb registers */
42#define DFB	1		/* data from bus */
43#define TAG	2		/* transfer access grant */
44
45/* Bits in dcount register */
46#define HMB	0x0f		/* how many bytes */
47#define APD	0x10		/* auto-poll data */
48
49/* Bits in error register */
50#define NRE	1		/* no response error */
51#define DLE	2		/* data lost error */
52
53/* Bits in ctrl register */
54#define TAR	1		/* transfer access request */
55#define DTB	2		/* data to bus */
56#define CRE	4		/* command response expected */
57#define ADB_RST	8		/* ADB reset */
58
59/* Bits in autopoll register */
60#define APE	1		/* autopoll enable */
61
62static volatile struct adb_regs __iomem *adb;
63static struct adb_request *current_req, *last_req;
64static DEFINE_SPINLOCK(macio_lock);
65
66static int macio_probe(void);
67static int macio_init(void);
68static irqreturn_t macio_adb_interrupt(int irq, void *arg);
69static int macio_send_request(struct adb_request *req, int sync);
70static int macio_adb_autopoll(int devs);
71static void macio_adb_poll(void);
72static int macio_adb_reset_bus(void);
73
74struct adb_driver macio_adb_driver = {
75	.name         = "MACIO",
76	.probe        = macio_probe,
77	.init         = macio_init,
78	.send_request = macio_send_request,
79	.autopoll     = macio_adb_autopoll,
80	.poll         = macio_adb_poll,
81	.reset_bus    = macio_adb_reset_bus,
82};
83
84int macio_probe(void)
85{
86	struct device_node *np;
87
88	np = of_find_compatible_node(NULL, "adb", "chrp,adb0");
89	if (np) {
90		of_node_put(np);
91		return 0;
92	}
93	return -ENODEV;
94}
95
96int macio_init(void)
97{
98	struct device_node *adbs;
99	struct resource r;
100	unsigned int irq;
101
102	adbs = of_find_compatible_node(NULL, "adb", "chrp,adb0");
103	if (!adbs)
104		return -ENXIO;
105
106	if (of_address_to_resource(adbs, 0, &r)) {
107		of_node_put(adbs);
108		return -ENXIO;
109	}
110	adb = ioremap(r.start, sizeof(struct adb_regs));
111	if (!adb) {
112		of_node_put(adbs);
113		return -ENOMEM;
114	}
115
116	out_8(&adb->ctrl.r, 0);
117	out_8(&adb->intr.r, 0);
118	out_8(&adb->error.r, 0);
119	out_8(&adb->active_hi.r, 0xff); /* for now, set all devices active */
120	out_8(&adb->active_lo.r, 0xff);
121	out_8(&adb->autopoll.r, APE);
122
123	irq = irq_of_parse_and_map(adbs, 0);
124	of_node_put(adbs);
125	if (request_irq(irq, macio_adb_interrupt, 0, "ADB", (void *)0)) {
126		iounmap(adb);
127		printk(KERN_ERR "ADB: can't get irq %d\n", irq);
128		return -EAGAIN;
129	}
130	out_8(&adb->intr_enb.r, DFB | TAG);
131
132	printk("adb: mac-io driver 1.0 for unified ADB\n");
133
134	return 0;
135}
136
137static int macio_adb_autopoll(int devs)
138{
139	unsigned long flags;
140
141	spin_lock_irqsave(&macio_lock, flags);
142	out_8(&adb->active_hi.r, devs >> 8);
143	out_8(&adb->active_lo.r, devs);
144	out_8(&adb->autopoll.r, devs? APE: 0);
145	spin_unlock_irqrestore(&macio_lock, flags);
146	return 0;
147}
148
149static int macio_adb_reset_bus(void)
150{
151	unsigned long flags;
152	int timeout = 1000000;
153
154	/* Hrm... we may want to not lock interrupts for so
155	 * long ... oh well, who uses that chip anyway ? :)
156	 * That function will be seldom used during boot
157	 * on rare machines, so...
158	 */
159	spin_lock_irqsave(&macio_lock, flags);
160	out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | ADB_RST);
161	while ((in_8(&adb->ctrl.r) & ADB_RST) != 0) {
162		if (--timeout == 0) {
163			out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) & ~ADB_RST);
164			spin_unlock_irqrestore(&macio_lock, flags);
165			return -1;
166		}
167	}
168	spin_unlock_irqrestore(&macio_lock, flags);
169	return 0;
170}
171
172/* Send an ADB command */
173static int macio_send_request(struct adb_request *req, int sync)
174{
175	unsigned long flags;
176	int i;
177
178	if (req->data[0] != ADB_PACKET)
179		return -EINVAL;
180
181	for (i = 0; i < req->nbytes - 1; ++i)
182		req->data[i] = req->data[i+1];
183	--req->nbytes;
184
185	req->next = NULL;
186	req->sent = 0;
187	req->complete = 0;
188	req->reply_len = 0;
189
190	spin_lock_irqsave(&macio_lock, flags);
191	if (current_req) {
192		last_req->next = req;
193		last_req = req;
194	} else {
195		current_req = last_req = req;
196		out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
197	}
198	spin_unlock_irqrestore(&macio_lock, flags);
199
200	if (sync) {
201		while (!req->complete)
202			macio_adb_poll();
203	}
204
205	return 0;
206}
207
208static irqreturn_t macio_adb_interrupt(int irq, void *arg)
209{
210	int i, n, err;
211	struct adb_request *req = NULL;
212	unsigned char ibuf[16];
213	int ibuf_len = 0;
214	int complete = 0;
215	int autopoll = 0;
216	int handled = 0;
217
218	spin_lock(&macio_lock);
219	if (in_8(&adb->intr.r) & TAG) {
220		handled = 1;
221		req = current_req;
222		if (req) {
223			/* put the current request in */
224			for (i = 0; i < req->nbytes; ++i)
225				out_8(&adb->data[i].r, req->data[i]);
226			out_8(&adb->dcount.r, req->nbytes & HMB);
227			req->sent = 1;
228			if (req->reply_expected) {
229				out_8(&adb->ctrl.r, DTB + CRE);
230			} else {
231				out_8(&adb->ctrl.r, DTB);
232				current_req = req->next;
233				complete = 1;
234				if (current_req)
235					out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
236			}
237		}
238		out_8(&adb->intr.r, 0);
239	}
240
241	if (in_8(&adb->intr.r) & DFB) {
242		handled = 1;
243		err = in_8(&adb->error.r);
244		if (current_req && current_req->sent) {
245			/* this is the response to a command */
246			req = current_req;
247			if (err == 0) {
248				req->reply_len = in_8(&adb->dcount.r) & HMB;
249				for (i = 0; i < req->reply_len; ++i)
250					req->reply[i] = in_8(&adb->data[i].r);
251			}
252			current_req = req->next;
253			complete = 1;
254			if (current_req)
255				out_8(&adb->ctrl.r, in_8(&adb->ctrl.r) | TAR);
256		} else if (err == 0) {
257			/* autopoll data */
258			n = in_8(&adb->dcount.r) & HMB;
259			for (i = 0; i < n; ++i)
260				ibuf[i] = in_8(&adb->data[i].r);
261			ibuf_len = n;
262			autopoll = (in_8(&adb->dcount.r) & APD) != 0;
263		}
264		out_8(&adb->error.r, 0);
265		out_8(&adb->intr.r, 0);
266	}
267	spin_unlock(&macio_lock);
268	if (complete && req) {
269	    void (*done)(struct adb_request *) = req->done;
270	    mb();
271	    req->complete = 1;
272	    /* Here, we assume that if the request has a done member, the
273    	     * struct request will survive to setting req->complete to 1
274	     */
275	    if (done)
276		(*done)(req);
277	}
278	if (ibuf_len)
279		adb_input(ibuf, ibuf_len, autopoll);
280
281	return IRQ_RETVAL(handled);
282}
283
284static void macio_adb_poll(void)
285{
286	unsigned long flags;
287
288	local_irq_save(flags);
289	if (in_8(&adb->intr.r) != 0)
290		macio_adb_interrupt(0, NULL);
291	local_irq_restore(flags);
292}
293