ctlreg.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *	Copyright IBM Corp. 1999, 2023
  4 */
  5
  6#include <linux/irqflags.h>
  7#include <linux/spinlock.h>
  8#include <linux/export.h>
  9#include <linux/kernel.h>
 10#include <linux/init.h>
 11#include <linux/smp.h>
 12#include <linux/cache.h>
 13#include <asm/abs_lowcore.h>
 14#include <asm/ctlreg.h>
 15
 16/*
 17 * ctl_lock guards access to global control register contents which
 18 * are kept in the control register save area within absolute lowcore
 19 * at physical address zero.
 20 */
 21static DEFINE_SPINLOCK(system_ctl_lock);
 22
 23void system_ctlreg_lock(void)
 24	__acquires(&system_ctl_lock)
 25{
 26	spin_lock(&system_ctl_lock);
 27}
 28
 29void system_ctlreg_unlock(void)
 30	__releases(&system_ctl_lock)
 31{
 32	spin_unlock(&system_ctl_lock);
 33}
 34
 35static bool system_ctlreg_area_init __ro_after_init;
 36
 37void __init system_ctlreg_init_save_area(struct lowcore *lc)
 38{
 39	struct lowcore *abs_lc;
 40
 41	abs_lc = get_abs_lowcore();
 42	__local_ctl_store(0, 15, lc->cregs_save_area);
 43	__local_ctl_store(0, 15, abs_lc->cregs_save_area);
 44	put_abs_lowcore(abs_lc);
 45	system_ctlreg_area_init = true;
 46}
 47
 48struct ctlreg_parms {
 49	unsigned long andval;
 50	unsigned long orval;
 51	unsigned long val;
 52	int request;
 53	int cr;
 54};
 55
 56static void ctlreg_callback(void *info)
 57{
 58	struct ctlreg_parms *pp = info;
 59	struct ctlreg regs[16];
 60
 61	__local_ctl_store(0, 15, regs);
 62	if (pp->request == CTLREG_LOAD) {
 63		regs[pp->cr].val = pp->val;
 64	} else {
 65		regs[pp->cr].val &= pp->andval;
 66		regs[pp->cr].val |= pp->orval;
 67	}
 68	__local_ctl_load(0, 15, regs);
 69}
 70
 71static void system_ctlreg_update(void *info)
 72{
 73	unsigned long flags;
 74
 75	if (system_state == SYSTEM_BOOTING) {
 76		/*
 77		 * For very early calls do not call on_each_cpu()
 78		 * since not everything might be setup.
 79		 */
 80		local_irq_save(flags);
 81		ctlreg_callback(info);
 82		local_irq_restore(flags);
 83	} else {
 84		on_each_cpu(ctlreg_callback, info, 1);
 85	}
 86}
 87
 88void system_ctlreg_modify(unsigned int cr, unsigned long data, int request)
 89{
 90	struct ctlreg_parms pp = { .cr = cr, .request = request, };
 91	struct lowcore *abs_lc;
 92
 93	switch (request) {
 94	case CTLREG_SET_BIT:
 95		pp.orval  = 1UL << data;
 96		pp.andval = -1UL;
 97		break;
 98	case CTLREG_CLEAR_BIT:
 99		pp.orval  = 0;
100		pp.andval = ~(1UL << data);
101		break;
102	case CTLREG_LOAD:
103		pp.val = data;
104		break;
105	}
106	if (system_ctlreg_area_init) {
107		system_ctlreg_lock();
108		abs_lc = get_abs_lowcore();
109		if (request == CTLREG_LOAD) {
110			abs_lc->cregs_save_area[cr].val = pp.val;
111		} else {
112			abs_lc->cregs_save_area[cr].val &= pp.andval;
113			abs_lc->cregs_save_area[cr].val |= pp.orval;
114		}
115		put_abs_lowcore(abs_lc);
116		system_ctlreg_update(&pp);
117		system_ctlreg_unlock();
118	} else {
119		system_ctlreg_update(&pp);
120	}
121}
122EXPORT_SYMBOL(system_ctlreg_modify);