diff mbox series

[RFC,6/6] irqchip/gic-v3: Re-init GIC hardware upon hibernation restore

Message ID 1652860121-24092-7-git-send-email-quic_vivekuma@quicinc.com (mailing list archive)
State New
Headers show
Series Bootloader based hibernation | expand

Commit Message

Vivek Kumar May 18, 2022, 7:48 a.m. UTC 
Code added in this patch takes backup of different set of
registers during hibernation suspend. On receiving hibernation
restore callback, it restores register values from backup. This
ensures state of hardware to be same just before hibernation and
after restore.

Signed-off-by: Vivek Kumar <quic_vivekuma@quicinc.com>
Signed-off-by: Prasanna Kumar <quic_kprasan@quicinc.com>
---
 drivers/irqchip/irq-gic-v3.c | 138 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 136 insertions(+), 2 deletions(-)

Comments

Marc Zyngier May 19, 2022, 7:59 a.m. UTC | #1 
Hi Vivek,

On Wed, 18 May 2022 08:48:41 +0100,
Vivek Kumar <quic_vivekuma@quicinc.com> wrote:
> 
> Code added in this patch takes backup of different set of
> registers during hibernation suspend. On receiving hibernation
> restore callback, it restores register values from backup. This
> ensures state of hardware to be same just before hibernation and
> after restore.
> 
> Signed-off-by: Vivek Kumar <quic_vivekuma@quicinc.com>
> Signed-off-by: Prasanna Kumar <quic_kprasan@quicinc.com>
> ---
>  drivers/irqchip/irq-gic-v3.c | 138 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 136 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 2be8dea..442d32f 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -29,6 +29,10 @@
>  #include <asm/smp_plat.h>
>  #include <asm/virt.h>
>  
> +#include <linux/syscore_ops.h>
> +#include <linux/suspend.h>
> +#include <linux/notifier.h>
> +
>  #include "irq-gic-common.h"
>  
>  #define GICD_INT_NMI_PRI	(GICD_INT_DEF_PRI & ~0x80)
> @@ -56,6 +60,14 @@ struct gic_chip_data {
>  	bool			has_rss;
>  	unsigned int		ppi_nr;
>  	struct partition_desc	**ppi_descs;
> +#ifdef CONFIG_HIBERNATION
> +	unsigned int enabled_irqs[32];
> +	unsigned int active_irqs[32];
> +	unsigned int irq_edg_lvl[64];
> +	unsigned int ppi_edg_lvl;
> +	unsigned int enabled_sgis;
> +	unsigned int pending_sgis;
> +#endif

This is either way too much, or way too little. Just restoring these
registers is nowhere near enough, as you are completely ignoring the
ITS, so this will leave the machine broken for anything that requires
LPIs.

But If the bootloader is supposed to replace the kernel to put the HW
in a state where the GIC is usable again, why do we need any of this?

Hibernation relies on a basic promise: the secondary kernel is entered
with the HW in a reasonable state, and the basic infrastructure
(specially for stuff that can be only programmed once per boot such as
the RD tables) is already available. If the bootloader is going to do
the work of the initial kernel, then it must do it fully, and not
require this sort of random sprinkling all over the shop.

Effectively, there is an ABI between the primary kernel and the
secondary, and I don't see why this interface should change to paper
over what I see as the deficiencies of the bootloader.

Am I missing anything?

Thanks,

	M.
diff mbox series

Patch

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 2be8dea..442d32f 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -29,6 +29,10 @@ 
 #include <asm/smp_plat.h>
 #include <asm/virt.h>
 
+#include <linux/syscore_ops.h>
+#include <linux/suspend.h>
+#include <linux/notifier.h>
+
 #include "irq-gic-common.h"
 
 #define GICD_INT_NMI_PRI	(GICD_INT_DEF_PRI & ~0x80)
@@ -56,6 +60,14 @@  struct gic_chip_data {
 	bool			has_rss;
 	unsigned int		ppi_nr;
 	struct partition_desc	**ppi_descs;
+#ifdef CONFIG_HIBERNATION
+	unsigned int enabled_irqs[32];
+	unsigned int active_irqs[32];
+	unsigned int irq_edg_lvl[64];
+	unsigned int ppi_edg_lvl;
+	unsigned int enabled_sgis;
+	unsigned int pending_sgis;
+#endif
 };
 
 static struct gic_chip_data gic_data __read_mostly;
@@ -170,6 +182,9 @@  static enum gic_intid_range get_intid_range(struct irq_data *d)
 	return __get_intid_range(d->hwirq);
 }
 
+static void gic_dist_init(void);
+static void gic_cpu_init(void);
+
 static inline unsigned int gic_irq(struct irq_data *d)
 {
 	return d->hwirq;
@@ -828,7 +843,7 @@  static bool gic_has_group0(void)
 	return val != 0;
 }
 
-static void __init gic_dist_init(void)
+static void gic_dist_init(void)
 {
 	unsigned int i;
 	u64 affinity;
@@ -1399,6 +1414,120 @@  static void gic_cpu_pm_init(void)
 static inline void gic_cpu_pm_init(void) { }
 #endif /* CONFIG_CPU_PM */
 
+#ifdef CONFIG_PM
+#ifdef CONFIG_HIBERNATION
+extern int in_suspend;
+static bool hibernation;
+
+static int gic_suspend_notifier(struct notifier_block *nb,
+				unsigned long event,
+				void *dummy)
+{
+	if (event == PM_HIBERNATION_PREPARE)
+		hibernation = true;
+	else if (event == PM_POST_HIBERNATION)
+		hibernation = false;
+	return NOTIFY_OK;
+}
+
+static struct notifier_block gic_notif_block = {
+	.notifier_call = gic_suspend_notifier,
+};
+
+static void gic_hibernation_suspend(void)
+{
+	int i;
+	void __iomem *base = gic_data.dist_base;
+	void __iomem *rdist_base = gic_data_rdist_sgi_base();
+
+	gic_data.enabled_sgis = readl_relaxed(rdist_base + GICD_ISENABLER);
+	gic_data.pending_sgis = readl_relaxed(rdist_base + GICD_ISPENDR);
+	/* Store edge level for PPIs by reading GICR_ICFGR1 */
+	gic_data.ppi_edg_lvl = readl_relaxed(rdist_base + GICR_ICFGR0 + 4);
+
+	for (i = 0; i * 32 < GIC_LINE_NR; i++) {
+		gic_data.enabled_irqs[i] = readl_relaxed(base +
+						GICD_ISENABLER + i * 4);
+		gic_data.active_irqs[i] = readl_relaxed(base +
+						GICD_ISPENDR + i * 4);
+	}
+
+	for (i = 2; i < GIC_LINE_NR / 16; i++)
+		gic_data.irq_edg_lvl[i] = readl_relaxed(base +
+						GICD_ICFGR + i * 4);
+}
+#endif
+
+static int gic_suspend(void)
+{
+#ifdef CONFIG_HIBERNATION
+	if (unlikely(hibernation))
+		gic_hibernation_suspend();
+#endif
+	return 0;
+}
+
+void gic_resume(void)
+{
+#ifdef CONFIG_HIBERNATION
+	int i;
+	void __iomem *base = gic_data.dist_base;
+	void __iomem *rdist_base = gic_data_rdist_sgi_base();
+
+	/*
+	 * in_suspend is defined in hibernate.c and will be 0 during
+	 * hibernation restore case. Also it willl be 0 for suspend to ram case
+	 * and similar cases. Underlying code will not get executed in regular
+	 * cases and will be executed only for hibernation restore.
+	 */
+	if (unlikely((in_suspend == 0 && hibernation))) {
+		pr_info("Re-initializing gic in hibernation restore\n");
+		gic_dist_init();
+		gic_cpu_init();
+		/* Activate and enable SGIs and PPIs */
+		writel_relaxed(gic_data.enabled_sgis,
+			       rdist_base + GICD_ISENABLER);
+		writel_relaxed(gic_data.pending_sgis,
+			       rdist_base + GICD_ISPENDR);
+		/* Restore edge and level triggers for PPIs from GICR_ICFGR1 */
+		writel_relaxed(gic_data.ppi_edg_lvl,
+			       rdist_base + GICR_ICFGR0 + 4);
+
+		/* Restore edge and level triggers */
+		for (i = 2; i < GIC_LINE_NR / 16; i++)
+			writel_relaxed(gic_data.irq_edg_lvl[i],
+					base + GICD_ICFGR + i * 4);
+		gic_dist_wait_for_rwp();
+
+		/* Activate and enable interrupts from backup */
+		for (i = 0; i * 32 < GIC_LINE_NR; i++) {
+			writel_relaxed(gic_data.active_irqs[i],
+				       base + GICD_ISPENDR + i * 4);
+
+			writel_relaxed(gic_data.enabled_irqs[i],
+				       base + GICD_ISENABLER + i * 4);
+		}
+		gic_dist_wait_for_rwp();
+	}
+#endif
+}
+EXPORT_SYMBOL_GPL(gic_resume);
+
+static struct syscore_ops gic_syscore_ops = {
+	.suspend = gic_suspend,
+	.resume = gic_resume,
+};
+
+static void gic_syscore_init(void)
+{
+	register_syscore_ops(&gic_syscore_ops);
+}
+
+#else
+static inline void gic_syscore_init(void) { }
+void gic_resume(void) { }
+#endif
+
 static struct irq_chip gic_chip = {
 	.name			= "GICv3",
 	.irq_mask		= gic_mask_irq,
@@ -1887,6 +2016,7 @@  static int __init gic_init_bases(void __iomem *dist_base,
 	gic_cpu_init();
 	gic_smp_init();
 	gic_cpu_pm_init();
+	gic_syscore_init();
 
 	if (gic_dist_supports_lpis()) {
 		its_init(handle, &gic_data.rdists, gic_data.domain);
@@ -2092,7 +2222,11 @@  static int __init gic_of_init(struct device_node *node, struct device_node *pare
 			     redist_stride, &node->fwnode);
 	if (err)
 		goto out_unmap_rdist;
-
+#ifdef CONFIG_HIBERNATION
+	err = register_pm_notifier(&gic_notif_block);
+	if (err)
+		goto out_unmap_rdist;
+#endif
 	gic_populate_ppi_partitions(node);
 
 	if (static_branch_likely(&supports_deactivate_key))