1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * (C) Copyright 2018
4  * Mario Six, Guntermann & Drunck GmbH, mario.six@gdsys.cc
5  */
6 
7 #include <common.h>
8 #include <board.h>
9 #include <clk.h>
10 #include <dm.h>
11 #include <timer.h>
12 #include <watchdog.h>
13 
14 DECLARE_GLOBAL_DATA_PTR;
15 
16 /**
17  * struct mpc83xx_timer_priv - Private data structure for MPC83xx timer driver
18  * @decrementer_count: Value to which the decrementer register should be re-set
19  *		       to when a timer interrupt occurs, thus determines the
20  *		       interrupt frequency (value for 1e6/HZ microseconds)
21  * @timestamp:         Counter for the number of timer interrupts that have
22  *		       occurred (i.e. can be used to trigger events
23  *		       periodically in the timer interrupt)
24  */
25 struct mpc83xx_timer_priv {
26 	uint decrementer_count;
27 	ulong timestamp;
28 };
29 
30 /*
31  * Bitmask for enabling the time base in the SPCR (System Priority
32  * Configuration Register)
33  */
34 static const u32 SPCR_TBEN_MASK = BIT(31 - 9);
35 
36 /**
37  * get_dec() - Get the value of the decrementer register
38  *
39  * Return: The value of the decrementer register
40  */
41 static inline unsigned long get_dec(void)
42 {
43 	unsigned long val;
44 
45 	asm volatile ("mfdec %0" : "=r" (val) : );
46 
47 	return val;
48 }
49 
50 /**
51  * set_dec() - Set the value of the decrementer register
52  * @val: The value of the decrementer register to be set
53  */
54 static inline void set_dec(unsigned long val)
55 {
56 	if (val)
57 		asm volatile ("mtdec %0"::"r" (val));
58 }
59 
60 /**
61  * mftbu() - Get value of TBU (upper time base) register
62  *
63  * Return: Value of the TBU register
64  */
65 static inline u32 mftbu(void)
66 {
67 	u32 rval;
68 
69 	asm volatile("mftbu %0" : "=r" (rval));
70 	return rval;
71 }
72 
73 /**
74  * mftb() - Get value of TBL (lower time base) register
75  *
76  * Return: Value of the TBL register
77  */
78 static inline u32 mftb(void)
79 {
80 	u32 rval;
81 
82 	asm volatile("mftb %0" : "=r" (rval));
83 	return rval;
84 }
85 
86 /*
87  * TODO(mario.six@gdsys.cc): This should really be done by timer_init, and the
88  * interrupt init should go into a interrupt driver.
89  */
90 int interrupt_init(void)
91 {
92 	immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
93 	struct udevice *csb;
94 	struct udevice *board;
95 	struct udevice *timer;
96 	struct mpc83xx_timer_priv *timer_priv;
97 	struct clk clock;
98 	int ret;
99 
100 	ret = uclass_first_device_err(UCLASS_TIMER, &timer);
101 	if (ret) {
102 		debug("%s: Could not find timer device (error: %d)",
103 		      __func__, ret);
104 		return ret;
105 	}
106 
107 	timer_priv = dev_get_priv(timer);
108 
109 	if (board_get(&board)) {
110 		debug("%s: board device could not be fetched.\n", __func__);
111 		return -ENOENT;
112 	}
113 
114 	ret = uclass_get_device_by_phandle(UCLASS_SIMPLE_BUS, board,
115 					   "csb", &csb);
116 	if (ret) {
117 		debug("%s: Could not retrieve CSB device (error: %d)",
118 		      __func__, ret);
119 		return ret;
120 	}
121 
122 	ret = clk_get_by_index(csb, 0, &clock);
123 	if (ret) {
124 		debug("%s: Could not retrieve clock (error: %d)",
125 		      __func__, ret);
126 		return ret;
127 	}
128 
129 	timer_priv->decrementer_count = (clk_get_rate(&clock) / 4)
130 					/ CONFIG_SYS_HZ;
131 	/* Enable e300 time base */
132 	setbits_be32(&immr->sysconf.spcr, SPCR_TBEN_MASK);
133 
134 	set_dec(timer_priv->decrementer_count);
135 
136 	/* Switch on interrupts */
137 	set_msr(get_msr() | MSR_EE);
138 
139 	return 0;
140 }
141 
142 /**
143  * timer_interrupt() - Handler for the timer interrupt
144  * @regs: Array of register values
145  */
146 void timer_interrupt(struct pt_regs *regs)
147 {
148 	struct udevice *timer = gd->timer;
149 	struct mpc83xx_timer_priv *priv;
150 
151 	/*
152 	 * During initialization, gd->timer might not be set yet, but the timer
153 	 * interrupt may already be enabled. In this case, wait for the
154 	 * initialization to complete
155 	 */
156 	if (!timer)
157 		return;
158 
159 	priv = dev_get_priv(timer);
160 
161 	/* Restore Decrementer Count */
162 	set_dec(priv->decrementer_count);
163 
164 	priv->timestamp++;
165 
166 #if defined(CONFIG_WATCHDOG) || defined(CONFIG_HW_WATCHDOG)
167 	if ((timestamp % (CONFIG_SYS_WATCHDOG_FREQ)) == 0)
168 		WATCHDOG_RESET();
169 #endif    /* CONFIG_WATCHDOG || CONFIG_HW_WATCHDOG */
170 
171 #ifdef CONFIG_LED_STATUS
172 	status_led_tick(priv->timestamp);
173 #endif /* CONFIG_LED_STATUS */
174 
175 #ifdef CONFIG_SHOW_ACTIVITY
176 	board_show_activity(priv->timestamp);
177 #endif /* CONFIG_SHOW_ACTIVITY */
178 }
179 
180 void wait_ticks(ulong ticks)
181 {
182 	ulong end = get_ticks() + ticks;
183 
184 	while (end > get_ticks())
185 		WATCHDOG_RESET();
186 }
187 
188 static int mpc83xx_timer_get_count(struct udevice *dev, u64 *count)
189 {
190 	u32 tbu, tbl;
191 
192 	/*
193 	 * To make sure that no tbl overflow occurred between reading tbl and
194 	 * tbu, read tbu again, and compare it with the previously read tbu
195 	 * value: If they're different, a tbl overflow has occurred.
196 	 */
197 	do {
198 		tbu = mftbu();
199 		tbl = mftb();
200 	} while (tbu != mftbu());
201 
202 	*count = (tbu * 0x10000ULL) + tbl;
203 
204 	return 0;
205 }
206 
207 static int mpc83xx_timer_probe(struct udevice *dev)
208 {
209 	struct timer_dev_priv *uc_priv = dev->uclass_priv;
210 	struct clk clock;
211 	int ret;
212 
213 	ret = interrupt_init();
214 	if (ret) {
215 		debug("%s: interrupt_init failed (err = %d)\n",
216 		      dev->name, ret);
217 		return ret;
218 	}
219 
220 	ret = clk_get_by_index(dev, 0, &clock);
221 	if (ret) {
222 		debug("%s: Could not retrieve clock (err = %d)\n",
223 		      dev->name, ret);
224 		return ret;
225 	}
226 
227 	uc_priv->clock_rate = (clk_get_rate(&clock) + 3L) / 4L;
228 
229 	return 0;
230 }
231 
232 static const struct timer_ops mpc83xx_timer_ops = {
233 	.get_count = mpc83xx_timer_get_count,
234 };
235 
236 static const struct udevice_id mpc83xx_timer_ids[] = {
237 	{ .compatible = "fsl,mpc83xx-timer" },
238 	{ /* sentinel */ }
239 };
240 
241 U_BOOT_DRIVER(mpc83xx_timer) = {
242 	.name	= "mpc83xx_timer",
243 	.id	= UCLASS_TIMER,
244 	.of_match = mpc83xx_timer_ids,
245 	.probe = mpc83xx_timer_probe,
246 	.ops	= &mpc83xx_timer_ops,
247 	.flags = DM_FLAG_PRE_RELOC,
248 	.priv_auto_alloc_size = sizeof(struct mpc83xx_timer_priv),
249 };
250