1// SPDX-License-Identifier: GPL-2.0
2/*
3 * CPM serial console support.
4 *
5 * Copyright 2007 Freescale Semiconductor, Inc.
6 * Author: Scott Wood <scottwood@freescale.com>
7 *
8 * It is assumed that the firmware (or the platform file) has already set
9 * up the port.
10 */
11
12#include "types.h"
13#include "io.h"
14#include "ops.h"
15#include "page.h"
16
17struct cpm_scc {
18	u32 gsmrl;
19	u32 gsmrh;
20	u16 psmr;
21	u8 res1[2];
22	u16 todr;
23	u16 dsr;
24	u16 scce;
25	u8 res2[2];
26	u16 sccm;
27	u8 res3;
28	u8 sccs;
29	u8 res4[8];
30};
31
32struct cpm_smc {
33	u8 res1[2];
34	u16 smcmr;
35	u8 res2[2];
36	u8 smce;
37	u8 res3[3];
38	u8 smcm;
39	u8 res4[5];
40};
41
42struct cpm_param {
43	u16 rbase;
44	u16 tbase;
45	u8 rfcr;
46	u8 tfcr;
47	u16 mrblr;
48	u32 rstate;
49	u8 res1[4];
50	u16 rbptr;
51	u8 res2[6];
52	u32 tstate;
53	u8 res3[4];
54	u16 tbptr;
55	u8 res4[6];
56	u16 maxidl;
57	u16 idlc;
58	u16 brkln;
59	u16 brkec;
60	u16 brkcr;
61	u16 rmask;
62	u8 res5[4];
63};
64
65struct cpm_bd {
66	u16 sc;   /* Status and Control */
67	u16 len;  /* Data length in buffer */
68	u8 *addr; /* Buffer address in host memory */
69};
70
71static void *cpcr;
72static struct cpm_param *param;
73static struct cpm_smc *smc;
74static struct cpm_scc *scc;
75static struct cpm_bd *tbdf, *rbdf;
76static u32 cpm_cmd;
77static void *cbd_addr;
78static u32 cbd_offset;
79
80static void (*do_cmd)(int op);
81static void (*enable_port)(void);
82static void (*disable_port)(void);
83
84#define CPM_CMD_STOP_TX     4
85#define CPM_CMD_RESTART_TX  6
86#define CPM_CMD_INIT_RX_TX  0
87
88static void cpm1_cmd(int op)
89{
90	while (in_be16(cpcr) & 1)
91		;
92
93	out_be16(cpcr, (op << 8) | cpm_cmd | 1);
94
95	while (in_be16(cpcr) & 1)
96		;
97}
98
99static void cpm2_cmd(int op)
100{
101	while (in_be32(cpcr) & 0x10000)
102		;
103
104	out_be32(cpcr, op | cpm_cmd | 0x10000);
105
106	while (in_be32(cpcr) & 0x10000)
107		;
108}
109
110static void smc_disable_port(void)
111{
112	do_cmd(CPM_CMD_STOP_TX);
113	out_be16(&smc->smcmr, in_be16(&smc->smcmr) & ~3);
114}
115
116static void scc_disable_port(void)
117{
118	do_cmd(CPM_CMD_STOP_TX);
119	out_be32(&scc->gsmrl, in_be32(&scc->gsmrl) & ~0x30);
120}
121
122static void smc_enable_port(void)
123{
124	out_be16(&smc->smcmr, in_be16(&smc->smcmr) | 3);
125	do_cmd(CPM_CMD_RESTART_TX);
126}
127
128static void scc_enable_port(void)
129{
130	out_be32(&scc->gsmrl, in_be32(&scc->gsmrl) | 0x30);
131	do_cmd(CPM_CMD_RESTART_TX);
132}
133
134static int cpm_serial_open(void)
135{
136	disable_port();
137
138	out_8(&param->rfcr, 0x10);
139	out_8(&param->tfcr, 0x10);
140	out_be16(&param->mrblr, 1);
141	out_be16(&param->maxidl, 0);
142	out_be16(&param->brkec, 0);
143	out_be16(&param->brkln, 0);
144	out_be16(&param->brkcr, 0);
145
146	rbdf = cbd_addr;
147	rbdf->addr = (u8 *)rbdf - 1;
148	rbdf->sc = 0xa000;
149	rbdf->len = 1;
150
151	tbdf = rbdf + 1;
152	tbdf->addr = (u8 *)rbdf - 2;
153	tbdf->sc = 0x2000;
154	tbdf->len = 1;
155
156	sync();
157	out_be16(&param->rbase, cbd_offset);
158	out_be16(&param->tbase, cbd_offset + sizeof(struct cpm_bd));
159
160	do_cmd(CPM_CMD_INIT_RX_TX);
161
162	enable_port();
163	return 0;
164}
165
166static void cpm_serial_putc(unsigned char c)
167{
168	while (tbdf->sc & 0x8000)
169		barrier();
170
171	sync();
172
173	tbdf->addr[0] = c;
174	eieio();
175	tbdf->sc |= 0x8000;
176}
177
178static unsigned char cpm_serial_tstc(void)
179{
180	barrier();
181	return !(rbdf->sc & 0x8000);
182}
183
184static unsigned char cpm_serial_getc(void)
185{
186	unsigned char c;
187
188	while (!cpm_serial_tstc())
189		;
190
191	sync();
192	c = rbdf->addr[0];
193	eieio();
194	rbdf->sc |= 0x8000;
195
196	return c;
197}
198
199int cpm_console_init(void *devp, struct serial_console_data *scdp)
200{
201	void *vreg[2];
202	u32 reg[2];
203	int is_smc = 0, is_cpm2 = 0;
204	void *parent, *muram;
205	void *muram_addr;
206	unsigned long muram_offset, muram_size;
207
208	if (dt_is_compatible(devp, "fsl,cpm1-smc-uart")) {
209		is_smc = 1;
210	} else if (dt_is_compatible(devp, "fsl,cpm2-scc-uart")) {
211		is_cpm2 = 1;
212	} else if (dt_is_compatible(devp, "fsl,cpm2-smc-uart")) {
213		is_cpm2 = 1;
214		is_smc = 1;
215	}
216
217	if (is_smc) {
218		enable_port = smc_enable_port;
219		disable_port = smc_disable_port;
220	} else {
221		enable_port = scc_enable_port;
222		disable_port = scc_disable_port;
223	}
224
225	if (is_cpm2)
226		do_cmd = cpm2_cmd;
227	else
228		do_cmd = cpm1_cmd;
229
230	if (getprop(devp, "fsl,cpm-command", &cpm_cmd, 4) < 4)
231		return -1;
232
233	if (dt_get_virtual_reg(devp, vreg, 2) < 2)
234		return -1;
235
236	if (is_smc)
237		smc = vreg[0];
238	else
239		scc = vreg[0];
240
241	param = vreg[1];
242
243	parent = get_parent(devp);
244	if (!parent)
245		return -1;
246
247	if (dt_get_virtual_reg(parent, &cpcr, 1) < 1)
248		return -1;
249
250	muram = finddevice("/soc/cpm/muram/data");
251	if (!muram)
252		return -1;
253
254	/* For bootwrapper-compatible device trees, we assume that the first
255	 * entry has at least 128 bytes, and that #address-cells/#data-cells
256	 * is one for both parent and child.
257	 */
258
259	if (dt_get_virtual_reg(muram, &muram_addr, 1) < 1)
260		return -1;
261
262	if (getprop(muram, "reg", reg, 8) < 8)
263		return -1;
264
265	muram_offset = reg[0];
266	muram_size = reg[1];
267
268	/* Store the buffer descriptors at the end of the first muram chunk.
269	 * For SMC ports on CPM2-based platforms, relocate the parameter RAM
270	 * just before the buffer descriptors.
271	 */
272
273	cbd_offset = muram_offset + muram_size - 2 * sizeof(struct cpm_bd);
274
275	if (is_cpm2 && is_smc) {
276		u16 *smc_base = (u16 *)param;
277		u16 pram_offset;
278
279		pram_offset = cbd_offset - 64;
280		pram_offset = _ALIGN_DOWN(pram_offset, 64);
281
282		disable_port();
283		out_be16(smc_base, pram_offset);
284		param = muram_addr - muram_offset + pram_offset;
285	}
286
287	cbd_addr = muram_addr - muram_offset + cbd_offset;
288
289	scdp->open = cpm_serial_open;
290	scdp->putc = cpm_serial_putc;
291	scdp->getc = cpm_serial_getc;
292	scdp->tstc = cpm_serial_tstc;
293
294	return 0;
295}
296