From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752509Ab2DBOQA (ORCPT ); Mon, 2 Apr 2012 10:16:00 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:12204 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751825Ab2DBOP7 convert rfc822-to-8bit (ORCPT ); Mon, 2 Apr 2012 10:15:59 -0400 Message-Id: <4F79D0BB020000780007C02D@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.0 Date: Mon, 02 Apr 2012 15:15:55 +0100 From: "Jan Beulich" To: , , Cc: Subject: [PATCH] x86: clear HPET configuration registers on startup Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org While Linux itself has been calling hpet_disable() for quite a while, having e.g. a secondary (kexec) kernel depend on such behavior of the primary (crashed) environment is fragile. It particularly broke until very recently when the primary environment was Xen based, as that hypervisor did not clear any of the HPET settings it may have used. Rather than blindly (and incompletely) clearing certain HPET settings in hpet_disable(), latch the config register settings during boot and restore then here. (Note on the hpet_set_mode() change: Now that we're clearing the level bit upon initialization, there's no need anymore to do so here.) Signed-off-by: Jan Beulich --- arch/x86/kernel/hpet.c | 59 ++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 51 insertions(+), 8 deletions(-) --- 3.4-rc1-x86-hpet.orig/arch/x86/kernel/hpet.c +++ 3.4-rc1-x86-hpet/arch/x86/kernel/hpet.c @@ -319,8 +319,6 @@ static void hpet_set_mode(enum clock_eve now = hpet_readl(HPET_COUNTER); cmp = now + (unsigned int) delta; cfg = hpet_readl(HPET_Tn_CFG(timer)); - /* Make sure we use edge triggered interrupts */ - cfg &= ~HPET_TN_LEVEL; cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL | HPET_TN_32BIT; hpet_writel(cfg, HPET_Tn_CFG(timer)); @@ -787,15 +785,16 @@ static int hpet_clocksource_register(voi return 0; } +static u32 *hpet_boot_cfg; + /** * hpet_enable - Try to setup the HPET timer. Returns 1 on success. */ int __init hpet_enable(void) { - unsigned long hpet_period; - unsigned int id; + u32 hpet_period, cfg, id; u64 freq; - int i; + unsigned int i, last; if (!is_hpet_capable()) return 0; @@ -847,15 +846,45 @@ int __init hpet_enable(void) id = hpet_readl(HPET_ID); hpet_print_config(); + last = (id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT; + #ifdef CONFIG_HPET_EMULATE_RTC /* * The legacy routing mode needs at least two channels, tick timer * and the rtc emulation channel. */ - if (!(id & HPET_ID_NUMBER)) + if (!last) goto out_nohpet; #endif + cfg = hpet_readl(HPET_CFG); + hpet_boot_cfg = kmalloc((last + 2) * sizeof(*hpet_boot_cfg), + GFP_KERNEL); + if (hpet_boot_cfg) + *hpet_boot_cfg = cfg; + else + pr_warn("HPET initial state will not be saved\n"); + cfg &= ~(HPET_CFG_ENABLE | HPET_CFG_LEGACY); + hpet_writel(cfg, HPET_Tn_CFG(i)); + if (cfg) + pr_warn("HPET: Unrecognized bits %#x set in global cfg\n", + cfg); + + for (i = 0; i <= last; ++i) { + cfg = hpet_readl(HPET_Tn_CFG(i)); + if (hpet_boot_cfg) + hpet_boot_cfg[i + 1] = cfg; + cfg &= ~(HPET_TN_ENABLE | HPET_TN_LEVEL | HPET_TN_FSB); + hpet_writel(cfg, HPET_Tn_CFG(i)); + cfg &= ~(HPET_TN_PERIODIC | HPET_TN_PERIODIC_CAP + | HPET_TN_64BIT_CAP | HPET_TN_32BIT | HPET_TN_ROUTE + | HPET_TN_FSB | HPET_TN_FSB_CAP); + if (cfg) + pr_warn("HPET: Unrecognized bits %#x set in cfg#%u\n", + cfg, i); + } + hpet_print_config(); + if (hpet_clocksource_register()) goto out_nohpet; @@ -923,14 +952,28 @@ fs_initcall(hpet_late_init); void hpet_disable(void) { if (is_hpet_capable() && hpet_virt_address) { - unsigned int cfg = hpet_readl(HPET_CFG); + unsigned int cfg = hpet_readl(HPET_CFG), id, last; - if (hpet_legacy_int_enabled) { + if (hpet_boot_cfg) + cfg = *hpet_boot_cfg; + else if (hpet_legacy_int_enabled) { cfg &= ~HPET_CFG_LEGACY; hpet_legacy_int_enabled = 0; } cfg &= ~HPET_CFG_ENABLE; hpet_writel(cfg, HPET_CFG); + + if (!hpet_boot_cfg) + return; + + id = hpet_readl(HPET_ID); + last = ((id & HPET_ID_NUMBER) >> HPET_ID_NUMBER_SHIFT); + + for (id = 0; id <= last; ++id) + hpet_writel(hpet_boot_cfg[id + 1], HPET_Tn_CFG(id)); + + if (*hpet_boot_cfg & HPET_CFG_ENABLE) + hpet_writel(*hpet_boot_cfg, HPET_CFG); } }