xref: /openbmc/linux/arch/powerpc/boot/cpm-serial.c (revision b2441318)
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 
17 struct 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 
32 struct 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 
42 struct 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 
65 struct 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 
71 static void *cpcr;
72 static struct cpm_param *param;
73 static struct cpm_smc *smc;
74 static struct cpm_scc *scc;
75 static struct cpm_bd *tbdf, *rbdf;
76 static u32 cpm_cmd;
77 static void *cbd_addr;
78 static u32 cbd_offset;
79 
80 static void (*do_cmd)(int op);
81 static void (*enable_port)(void);
82 static 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 
cpm1_cmd(int op)88 static 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 
cpm2_cmd(int op)99 static 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 
smc_disable_port(void)110 static 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 
scc_disable_port(void)116 static 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 
smc_enable_port(void)122 static 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 
scc_enable_port(void)128 static 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 
cpm_serial_open(void)134 static 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 
cpm_serial_putc(unsigned char c)166 static 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 
cpm_serial_tstc(void)178 static unsigned char cpm_serial_tstc(void)
179 {
180 	barrier();
181 	return !(rbdf->sc & 0x8000);
182 }
183 
cpm_serial_getc(void)184 static 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 
cpm_console_init(void * devp,struct serial_console_data * scdp)199 int 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