1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  linux/arch/arm/mach-sa1100/cpu-sa1110.c
4  *
5  *  Copyright (C) 2001 Russell King
6  *
7  * Note: there are two erratas that apply to the SA1110 here:
8  *  7 - SDRAM auto-power-up failure (rev A0)
9  * 13 - Corruption of internal register reads/writes following
10  *      SDRAM reads (rev A0, B0, B1)
11  *
12  * We ignore rev. A0 and B0 devices; I don't think they're worth supporting.
13  *
14  * The SDRAM type can be passed on the command line as cpu_sa1110.sdram=type
15  */
16 #include <linux/cpufreq.h>
17 #include <linux/delay.h>
18 #include <linux/init.h>
19 #include <linux/io.h>
20 #include <linux/kernel.h>
21 #include <linux/moduleparam.h>
22 #include <linux/types.h>
23 
24 #include <asm/cputype.h>
25 #include <asm/mach-types.h>
26 
27 #include <mach/generic.h>
28 #include <mach/hardware.h>
29 
30 #undef DEBUG
31 
32 struct sdram_params {
33 	const char name[20];
34 	u_char  rows;		/* bits				 */
35 	u_char  cas_latency;	/* cycles			 */
36 	u_char  tck;		/* clock cycle time (ns)	 */
37 	u_char  trcd;		/* activate to r/w (ns)		 */
38 	u_char  trp;		/* precharge to activate (ns)	 */
39 	u_char  twr;		/* write recovery time (ns)	 */
40 	u_short refresh;	/* refresh time for array (us)	 */
41 };
42 
43 struct sdram_info {
44 	u_int	mdcnfg;
45 	u_int	mdrefr;
46 	u_int	mdcas[3];
47 };
48 
49 static struct sdram_params sdram_tbl[] __initdata = {
50 	{	/* Toshiba TC59SM716 CL2 */
51 		.name		= "TC59SM716-CL2",
52 		.rows		= 12,
53 		.tck		= 10,
54 		.trcd		= 20,
55 		.trp		= 20,
56 		.twr		= 10,
57 		.refresh	= 64000,
58 		.cas_latency	= 2,
59 	}, {	/* Toshiba TC59SM716 CL3 */
60 		.name		= "TC59SM716-CL3",
61 		.rows		= 12,
62 		.tck		= 8,
63 		.trcd		= 20,
64 		.trp		= 20,
65 		.twr		= 8,
66 		.refresh	= 64000,
67 		.cas_latency	= 3,
68 	}, {	/* Samsung K4S641632D TC75 */
69 		.name		= "K4S641632D",
70 		.rows		= 14,
71 		.tck		= 9,
72 		.trcd		= 27,
73 		.trp		= 20,
74 		.twr		= 9,
75 		.refresh	= 64000,
76 		.cas_latency	= 3,
77 	}, {	/* Samsung K4S281632B-1H */
78 		.name           = "K4S281632B-1H",
79 		.rows		= 12,
80 		.tck		= 10,
81 		.trp		= 20,
82 		.twr		= 10,
83 		.refresh	= 64000,
84 		.cas_latency	= 3,
85 	}, {	/* Samsung KM416S4030CT */
86 		.name		= "KM416S4030CT",
87 		.rows		= 13,
88 		.tck		= 8,
89 		.trcd		= 24,	/* 3 CLKs */
90 		.trp		= 24,	/* 3 CLKs */
91 		.twr		= 16,	/* Trdl: 2 CLKs */
92 		.refresh	= 64000,
93 		.cas_latency	= 3,
94 	}, {	/* Winbond W982516AH75L CL3 */
95 		.name		= "W982516AH75L",
96 		.rows		= 16,
97 		.tck		= 8,
98 		.trcd		= 20,
99 		.trp		= 20,
100 		.twr		= 8,
101 		.refresh	= 64000,
102 		.cas_latency	= 3,
103 	}, {	/* Micron MT48LC8M16A2TG-75 */
104 		.name		= "MT48LC8M16A2TG-75",
105 		.rows		= 12,
106 		.tck		= 8,
107 		.trcd		= 20,
108 		.trp		= 20,
109 		.twr		= 8,
110 		.refresh	= 64000,
111 		.cas_latency	= 3,
112 	},
113 };
114 
115 static struct sdram_params sdram_params;
116 
117 /*
118  * Given a period in ns and frequency in khz, calculate the number of
119  * cycles of frequency in period.  Note that we round up to the next
120  * cycle, even if we are only slightly over.
121  */
ns_to_cycles(u_int ns,u_int khz)122 static inline u_int ns_to_cycles(u_int ns, u_int khz)
123 {
124 	return (ns * khz + 999999) / 1000000;
125 }
126 
127 /*
128  * Create the MDCAS register bit pattern.
129  */
set_mdcas(u_int * mdcas,int delayed,u_int rcd)130 static inline void set_mdcas(u_int *mdcas, int delayed, u_int rcd)
131 {
132 	u_int shift;
133 
134 	rcd = 2 * rcd - 1;
135 	shift = delayed + 1 + rcd;
136 
137 	mdcas[0]  = (1 << rcd) - 1;
138 	mdcas[0] |= 0x55555555 << shift;
139 	mdcas[1]  = mdcas[2] = 0x55555555 << (shift & 1);
140 }
141 
142 static void
sdram_calculate_timing(struct sdram_info * sd,u_int cpu_khz,struct sdram_params * sdram)143 sdram_calculate_timing(struct sdram_info *sd, u_int cpu_khz,
144 		       struct sdram_params *sdram)
145 {
146 	u_int mem_khz, sd_khz, trp, twr;
147 
148 	mem_khz = cpu_khz / 2;
149 	sd_khz = mem_khz;
150 
151 	/*
152 	 * If SDCLK would invalidate the SDRAM timings,
153 	 * run SDCLK at half speed.
154 	 *
155 	 * CPU steppings prior to B2 must either run the memory at
156 	 * half speed or use delayed read latching (errata 13).
157 	 */
158 	if ((ns_to_cycles(sdram->tck, sd_khz) > 1) ||
159 	    (read_cpuid_revision() < ARM_CPU_REV_SA1110_B2 && sd_khz < 62000))
160 		sd_khz /= 2;
161 
162 	sd->mdcnfg = MDCNFG & 0x007f007f;
163 
164 	twr = ns_to_cycles(sdram->twr, mem_khz);
165 
166 	/* trp should always be >1 */
167 	trp = ns_to_cycles(sdram->trp, mem_khz) - 1;
168 	if (trp < 1)
169 		trp = 1;
170 
171 	sd->mdcnfg |= trp << 8;
172 	sd->mdcnfg |= trp << 24;
173 	sd->mdcnfg |= sdram->cas_latency << 12;
174 	sd->mdcnfg |= sdram->cas_latency << 28;
175 	sd->mdcnfg |= twr << 14;
176 	sd->mdcnfg |= twr << 30;
177 
178 	sd->mdrefr = MDREFR & 0xffbffff0;
179 	sd->mdrefr |= 7;
180 
181 	if (sd_khz != mem_khz)
182 		sd->mdrefr |= MDREFR_K1DB2;
183 
184 	/* initial number of '1's in MDCAS + 1 */
185 	set_mdcas(sd->mdcas, sd_khz >= 62000,
186 		ns_to_cycles(sdram->trcd, mem_khz));
187 
188 #ifdef DEBUG
189 	printk(KERN_DEBUG "MDCNFG: %08x MDREFR: %08x MDCAS0: %08x MDCAS1: %08x MDCAS2: %08x\n",
190 		sd->mdcnfg, sd->mdrefr, sd->mdcas[0], sd->mdcas[1],
191 		sd->mdcas[2]);
192 #endif
193 }
194 
195 /*
196  * Set the SDRAM refresh rate.
197  */
sdram_set_refresh(u_int dri)198 static inline void sdram_set_refresh(u_int dri)
199 {
200 	MDREFR = (MDREFR & 0xffff000f) | (dri << 4);
201 	(void) MDREFR;
202 }
203 
204 /*
205  * Update the refresh period.  We do this such that we always refresh
206  * the SDRAMs within their permissible period.  The refresh period is
207  * always a multiple of the memory clock (fixed at cpu_clock / 2).
208  *
209  * FIXME: we don't currently take account of burst accesses here,
210  * but neither do Intels DM nor Angel.
211  */
212 static void
sdram_update_refresh(u_int cpu_khz,struct sdram_params * sdram)213 sdram_update_refresh(u_int cpu_khz, struct sdram_params *sdram)
214 {
215 	u_int ns_row = (sdram->refresh * 1000) >> sdram->rows;
216 	u_int dri = ns_to_cycles(ns_row, cpu_khz / 2) / 32;
217 
218 #ifdef DEBUG
219 	mdelay(250);
220 	printk(KERN_DEBUG "new dri value = %d\n", dri);
221 #endif
222 
223 	sdram_set_refresh(dri);
224 }
225 
226 /*
227  * Ok, set the CPU frequency.
228  */
sa1110_target(struct cpufreq_policy * policy,unsigned int ppcr)229 static int sa1110_target(struct cpufreq_policy *policy, unsigned int ppcr)
230 {
231 	struct sdram_params *sdram = &sdram_params;
232 	struct sdram_info sd;
233 	unsigned long flags;
234 	unsigned int unused;
235 
236 	sdram_calculate_timing(&sd, sa11x0_freq_table[ppcr].frequency, sdram);
237 
238 #if 0
239 	/*
240 	 * These values are wrong according to the SA1110 documentation
241 	 * and errata, but they seem to work.  Need to get a storage
242 	 * scope on to the SDRAM signals to work out why.
243 	 */
244 	if (policy->max < 147500) {
245 		sd.mdrefr |= MDREFR_K1DB2;
246 		sd.mdcas[0] = 0xaaaaaa7f;
247 	} else {
248 		sd.mdrefr &= ~MDREFR_K1DB2;
249 		sd.mdcas[0] = 0xaaaaaa9f;
250 	}
251 	sd.mdcas[1] = 0xaaaaaaaa;
252 	sd.mdcas[2] = 0xaaaaaaaa;
253 #endif
254 
255 	/*
256 	 * The clock could be going away for some time.  Set the SDRAMs
257 	 * to refresh rapidly (every 64 memory clock cycles).  To get
258 	 * through the whole array, we need to wait 262144 mclk cycles.
259 	 * We wait 20ms to be safe.
260 	 */
261 	sdram_set_refresh(2);
262 	if (!irqs_disabled())
263 		msleep(20);
264 	else
265 		mdelay(20);
266 
267 	/*
268 	 * Reprogram the DRAM timings with interrupts disabled, and
269 	 * ensure that we are doing this within a complete cache line.
270 	 * This means that we won't access SDRAM for the duration of
271 	 * the programming.
272 	 */
273 	local_irq_save(flags);
274 	asm("mcr p15, 0, %0, c7, c10, 4" : : "r" (0));
275 	udelay(10);
276 	__asm__ __volatile__("\n\
277 		b	2f					\n\
278 		.align	5					\n\
279 1:		str	%3, [%1, #0]		@ MDCNFG	\n\
280 		str	%4, [%1, #28]		@ MDREFR	\n\
281 		str	%5, [%1, #4]		@ MDCAS0	\n\
282 		str	%6, [%1, #8]		@ MDCAS1	\n\
283 		str	%7, [%1, #12]		@ MDCAS2	\n\
284 		str	%8, [%2, #0]		@ PPCR		\n\
285 		ldr	%0, [%1, #0]				\n\
286 		b	3f					\n\
287 2:		b	1b					\n\
288 3:		nop						\n\
289 		nop"
290 		: "=&r" (unused)
291 		: "r" (&MDCNFG), "r" (&PPCR), "0" (sd.mdcnfg),
292 		  "r" (sd.mdrefr), "r" (sd.mdcas[0]),
293 		  "r" (sd.mdcas[1]), "r" (sd.mdcas[2]), "r" (ppcr));
294 	local_irq_restore(flags);
295 
296 	/*
297 	 * Now, return the SDRAM refresh back to normal.
298 	 */
299 	sdram_update_refresh(sa11x0_freq_table[ppcr].frequency, sdram);
300 
301 	return 0;
302 }
303 
sa1110_cpu_init(struct cpufreq_policy * policy)304 static int __init sa1110_cpu_init(struct cpufreq_policy *policy)
305 {
306 	cpufreq_generic_init(policy, sa11x0_freq_table, 0);
307 	return 0;
308 }
309 
310 /* sa1110_driver needs __refdata because it must remain after init registers
311  * it with cpufreq_register_driver() */
312 static struct cpufreq_driver sa1110_driver __refdata = {
313 	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK |
314 			  CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
315 	.verify		= cpufreq_generic_frequency_table_verify,
316 	.target_index	= sa1110_target,
317 	.get		= sa11x0_getspeed,
318 	.init		= sa1110_cpu_init,
319 	.name		= "sa1110",
320 };
321 
sa1110_find_sdram(const char * name)322 static struct sdram_params *sa1110_find_sdram(const char *name)
323 {
324 	struct sdram_params *sdram;
325 
326 	for (sdram = sdram_tbl; sdram < sdram_tbl + ARRAY_SIZE(sdram_tbl);
327 	     sdram++)
328 		if (strcmp(name, sdram->name) == 0)
329 			return sdram;
330 
331 	return NULL;
332 }
333 
334 static char sdram_name[16];
335 
sa1110_clk_init(void)336 static int __init sa1110_clk_init(void)
337 {
338 	struct sdram_params *sdram;
339 	const char *name = sdram_name;
340 
341 	if (!cpu_is_sa1110())
342 		return -ENODEV;
343 
344 	if (!name[0]) {
345 		if (machine_is_assabet())
346 			name = "TC59SM716-CL3";
347 		if (machine_is_jornada720() || machine_is_h3600())
348 			name = "K4S281632B-1H";
349 	}
350 
351 	sdram = sa1110_find_sdram(name);
352 	if (sdram) {
353 		printk(KERN_DEBUG "SDRAM: tck: %d trcd: %d trp: %d"
354 			" twr: %d refresh: %d cas_latency: %d\n",
355 			sdram->tck, sdram->trcd, sdram->trp,
356 			sdram->twr, sdram->refresh, sdram->cas_latency);
357 
358 		memcpy(&sdram_params, sdram, sizeof(sdram_params));
359 
360 		return cpufreq_register_driver(&sa1110_driver);
361 	}
362 
363 	return 0;
364 }
365 
366 module_param_string(sdram, sdram_name, sizeof(sdram_name), 0);
367 arch_initcall(sa1110_clk_init);
368