1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 1995 Linus Torvalds
4 * Adapted from 'alpha' version by Gary Thomas
5 * Modified by Cort Dougan (cort@cs.nmt.edu)
6 * Modified for MBX using prep/chrp/pmac functions by Dan (dmalek@jlc.net)
7 * Further modified for generic 8xx by Dan.
8 */
9
10 /*
11 * bootup setup stuff..
12 */
13
14 #include <linux/kernel.h>
15 #include <linux/interrupt.h>
16 #include <linux/init.h>
17 #include <linux/time.h>
18 #include <linux/rtc.h>
19 #include <linux/fsl_devices.h>
20 #include <linux/of.h>
21 #include <linux/of_irq.h>
22
23 #include <asm/io.h>
24 #include <asm/8xx_immap.h>
25 #include <mm/mmu_decl.h>
26
27 #include "pic.h"
28
29 #include "mpc8xx.h"
30
31 /* A place holder for time base interrupts, if they are ever enabled. */
timebase_interrupt(int irq,void * dev)32 static irqreturn_t timebase_interrupt(int irq, void *dev)
33 {
34 printk ("timebase_interrupt()\n");
35
36 return IRQ_HANDLED;
37 }
38
get_freq(char * name,unsigned long * val)39 static int __init get_freq(char *name, unsigned long *val)
40 {
41 struct device_node *cpu;
42 const unsigned int *fp;
43 int found = 0;
44
45 /* The cpu node should have timebase and clock frequency properties */
46 cpu = of_get_cpu_node(0, NULL);
47
48 if (cpu) {
49 fp = of_get_property(cpu, name, NULL);
50 if (fp) {
51 found = 1;
52 *val = *fp;
53 }
54
55 of_node_put(cpu);
56 }
57
58 return found;
59 }
60
61 /* The decrementer counts at the system (internal) clock frequency divided by
62 * sixteen, or external oscillator divided by four. We force the processor
63 * to use system clock divided by sixteen.
64 */
mpc8xx_calibrate_decr(void)65 void __init mpc8xx_calibrate_decr(void)
66 {
67 struct device_node *cpu;
68 int irq, virq;
69
70 /* Unlock the SCCR. */
71 out_be32(&mpc8xx_immr->im_clkrstk.cark_sccrk, ~KAPWR_KEY);
72 out_be32(&mpc8xx_immr->im_clkrstk.cark_sccrk, KAPWR_KEY);
73
74 /* Force all 8xx processors to use divide by 16 processor clock. */
75 setbits32(&mpc8xx_immr->im_clkrst.car_sccr, 0x02000000);
76
77 /* Processor frequency is MHz.
78 */
79 ppc_proc_freq = 50000000;
80 if (!get_freq("clock-frequency", &ppc_proc_freq))
81 printk(KERN_ERR "WARNING: Estimating processor frequency "
82 "(not found)\n");
83
84 ppc_tb_freq = ppc_proc_freq / 16;
85 printk("Decrementer Frequency = 0x%lx\n", ppc_tb_freq);
86
87 /* Perform some more timer/timebase initialization. This used
88 * to be done elsewhere, but other changes caused it to get
89 * called more than once....that is a bad thing.
90 *
91 * First, unlock all of the registers we are going to modify.
92 * To protect them from corruption during power down, registers
93 * that are maintained by keep alive power are "locked". To
94 * modify these registers we have to write the key value to
95 * the key location associated with the register.
96 * Some boards power up with these unlocked, while others
97 * are locked. Writing anything (including the unlock code?)
98 * to the unlocked registers will lock them again. So, here
99 * we guarantee the registers are locked, then we unlock them
100 * for our use.
101 */
102 out_be32(&mpc8xx_immr->im_sitk.sitk_tbscrk, ~KAPWR_KEY);
103 out_be32(&mpc8xx_immr->im_sitk.sitk_rtcsck, ~KAPWR_KEY);
104 out_be32(&mpc8xx_immr->im_sitk.sitk_tbk, ~KAPWR_KEY);
105 out_be32(&mpc8xx_immr->im_sitk.sitk_tbscrk, KAPWR_KEY);
106 out_be32(&mpc8xx_immr->im_sitk.sitk_rtcsck, KAPWR_KEY);
107 out_be32(&mpc8xx_immr->im_sitk.sitk_tbk, KAPWR_KEY);
108
109 /* Disable the RTC one second and alarm interrupts. */
110 clrbits16(&mpc8xx_immr->im_sit.sit_rtcsc, (RTCSC_SIE | RTCSC_ALE));
111
112 /* Enable the RTC */
113 setbits16(&mpc8xx_immr->im_sit.sit_rtcsc, (RTCSC_RTF | RTCSC_RTE));
114
115 /* Enabling the decrementer also enables the timebase interrupts
116 * (or from the other point of view, to get decrementer interrupts
117 * we have to enable the timebase). The decrementer interrupt
118 * is wired into the vector table, nothing to do here for that.
119 */
120 cpu = of_get_cpu_node(0, NULL);
121 virq= irq_of_parse_and_map(cpu, 0);
122 of_node_put(cpu);
123 irq = virq_to_hw(virq);
124
125 out_be16(&mpc8xx_immr->im_sit.sit_tbscr,
126 ((1 << (7 - (irq / 2))) << 8) | (TBSCR_TBF | TBSCR_TBE));
127
128 if (request_irq(virq, timebase_interrupt, IRQF_NO_THREAD, "tbint",
129 NULL))
130 panic("Could not allocate timer IRQ!");
131 }
132
133 /* The RTC on the MPC8xx is an internal register.
134 * We want to protect this during power down, so we need to unlock,
135 * modify, and re-lock.
136 */
137
mpc8xx_set_rtc_time(struct rtc_time * tm)138 int mpc8xx_set_rtc_time(struct rtc_time *tm)
139 {
140 time64_t time;
141
142 time = rtc_tm_to_time64(tm);
143
144 out_be32(&mpc8xx_immr->im_sitk.sitk_rtck, KAPWR_KEY);
145 out_be32(&mpc8xx_immr->im_sit.sit_rtc, (u32)time);
146 out_be32(&mpc8xx_immr->im_sitk.sitk_rtck, ~KAPWR_KEY);
147
148 return 0;
149 }
150
mpc8xx_get_rtc_time(struct rtc_time * tm)151 void mpc8xx_get_rtc_time(struct rtc_time *tm)
152 {
153 unsigned long data;
154
155 /* Get time from the RTC. */
156 data = in_be32(&mpc8xx_immr->im_sit.sit_rtc);
157 rtc_time64_to_tm(data, tm);
158 return;
159 }
160
mpc8xx_restart(char * cmd)161 void __noreturn mpc8xx_restart(char *cmd)
162 {
163 local_irq_disable();
164
165 setbits32(&mpc8xx_immr->im_clkrst.car_plprcr, 0x00000080);
166 /* Clear the ME bit in MSR to cause checkstop on machine check
167 */
168 mtmsr(mfmsr() & ~0x1000);
169
170 in_8(&mpc8xx_immr->im_clkrst.res[0]);
171 panic("Restart failed\n");
172 }
173