Messages in this thread Patch in this message | | | From | Vladimir Oltean <> | Subject | [PATCH v2] irqchip/ls-extirq: use raw spinlocks for regmap to avoid invalid wait context | Date | Fri, 22 Jul 2022 23:40:19 +0300 |
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The irqchip->irq_set_type method is called by __irq_set_trigger() under the desc->lock raw spinlock.
The ls-extirq implementation, ls_extirq_irq_set_type(), uses an MMIO regmap created by of_syscon_register(), which uses plain spinlocks (the kind that are sleepable on RT).
Therefore, this is an invalid locking scheme for which we get a kernel splat stating just that ("[ BUG: Invalid wait context ]"), because the context in which the plain spinlock may sleep is atomic due to the raw spinlock. We need to go raw spinlocks all the way.
Make this driver create its own MMIO regmap, with use_raw_spinlock=true, and stop relying on syscon to provide it. Since the regmap we got from syscon belonged to the parent and this one belongs to us, the offset to the INTPCR register is now 0, because of the address translation that takes place through the device tree.
Another complication that we need to deal with is the fact that we need to parse the 'little-endian'/'big-endian' specifiers that exist in device trees for the parent ourselves now, since we no longer involve syscon.
And yet one final complication, due to the fact that this driver uses IRQCHIP_DECLARE rather than traditional platform devices with probe and remove methods, is that we cannot use devres, so we need to implement a full-blown cleanup procedure on the error path.
This patch depends on commit 67021f25d952 ("regmap: teach regmap to use raw spinlocks if requested in the config").
Fixes: 0dcd9f872769 ("irqchip: Add support for Layerscape external interrupt lines") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> --- v1->v2: create a separate regmap for the ls-extirq driver rather than relying on the one provided by syscon or modifying that.
For reference, v1 is at: https://lore.kernel.org/lkml/20210825205041.927788-3-vladimir.oltean@nxp.com/
For extra reviewer convenience, the ls-extirq appears in the following SoC device trees: https://elixir.bootlin.com/linux/v5.18.13/source/arch/arm64/boot/dts/freescale/fsl-ls208xa.dtsi#L289 https://elixir.bootlin.com/linux/v5.18.13/source/arch/arm64/boot/dts/freescale/fsl-ls1088a.dtsi#L249 https://elixir.bootlin.com/linux/v5.18.13/source/arch/arm64/boot/dts/freescale/fsl-ls1043a.dtsi#L319 https://elixir.bootlin.com/linux/v5.18.13/source/arch/arm64/boot/dts/freescale/fsl-ls1046a.dtsi#L325 https://elixir.bootlin.com/linux/v5.18.13/source/arch/arm64/boot/dts/freescale/fsl-lx2160a.dtsi#L682 https://elixir.bootlin.com/linux/v5.18.13/source/arch/arm/boot/dts/ls1021a.dtsi#L182
Patch tested on LX2160A and LS1021A.
drivers/irqchip/irq-ls-extirq.c | 81 +++++++++++++++++++++++---------- 1 file changed, 58 insertions(+), 23 deletions(-)
diff --git a/drivers/irqchip/irq-ls-extirq.c b/drivers/irqchip/irq-ls-extirq.c index 853b3972dbe7..94a22642b3f2 100644 --- a/drivers/irqchip/irq-ls-extirq.c +++ b/drivers/irqchip/irq-ls-extirq.c @@ -6,7 +6,7 @@ #include <linux/irqchip.h> #include <linux/irqdomain.h> #include <linux/of.h> -#include <linux/mfd/syscon.h> +#include <linux/of_address.h> #include <linux/regmap.h> #include <linux/slab.h> @@ -16,8 +16,7 @@ #define LS1021A_SCFGREVCR 0x200 struct ls_extirq_data { - struct regmap *syscon; - u32 intpcr; + struct regmap *regmap; bool is_ls1021a_or_ls1043a; u32 nirq; struct irq_fwspec map[MAXIRQ]; @@ -51,7 +50,10 @@ ls_extirq_set_type(struct irq_data *data, unsigned int type) default: return -EINVAL; } - regmap_update_bits(priv->syscon, priv->intpcr, mask, value); + /* INTPCR is the only register of our regmap, + * therefore its offset is 0 + */ + regmap_update_bits(priv->regmap, 0, mask, value); return irq_chip_set_type_parent(data, type); } @@ -143,48 +145,81 @@ ls_extirq_parse_map(struct ls_extirq_data *priv, struct device_node *node) static int __init ls_extirq_of_init(struct device_node *node, struct device_node *parent) { - + struct regmap_config extirq_regmap_config = { + .name = "intpcr", + .reg_bits = 32, + .val_bits = 32, + .reg_stride = 4, + .use_raw_spinlock = true, + }; struct irq_domain *domain, *parent_domain; struct ls_extirq_data *priv; + void __iomem *base; int ret; parent_domain = irq_find_host(parent); if (!parent_domain) { pr_err("Cannot find parent domain\n"); - return -ENODEV; + ret = -ENODEV; + goto err_irq_find_host; } priv = kzalloc(sizeof(*priv), GFP_KERNEL); - if (!priv) - return -ENOMEM; - - priv->syscon = syscon_node_to_regmap(node->parent); - if (IS_ERR(priv->syscon)) { - ret = PTR_ERR(priv->syscon); - pr_err("Failed to lookup parent regmap\n"); - goto out; + if (!priv) { + ret = -ENOMEM; + goto err_alloc_priv; + } + + /* All extirq OF nodes are under a scfg/syscon node with + * the 'ranges' property + */ + base = of_iomap(node, 0); + if (!base) { + pr_err("Cannot ioremap OF node %pOF\n", node); + ret = -ENOMEM; + goto err_iomap; } - ret = of_property_read_u32(node, "reg", &priv->intpcr); - if (ret) { - pr_err("Missing INTPCR offset value\n"); - goto out; + + /* Parse the parent device's DT node for an endianness specification */ + if (of_property_read_bool(parent, "big-endian")) + extirq_regmap_config.val_format_endian = REGMAP_ENDIAN_BIG; + else if (of_property_read_bool(parent, "little-endian")) + extirq_regmap_config.val_format_endian = REGMAP_ENDIAN_LITTLE; + else if (of_property_read_bool(parent, "native-endian")) + extirq_regmap_config.val_format_endian = REGMAP_ENDIAN_NATIVE; + + priv->regmap = regmap_init_mmio(NULL, base, &extirq_regmap_config); + if (IS_ERR(priv->regmap)) { + pr_err("Cannot create MMIO regmap: %pe\n", priv->regmap); + ret = PTR_ERR(priv->regmap); + goto err_regmap_init; } ret = ls_extirq_parse_map(priv, node); if (ret) - goto out; + goto err_parse_map; priv->is_ls1021a_or_ls1043a = of_device_is_compatible(node, "fsl,ls1021a-extirq") || of_device_is_compatible(node, "fsl,ls1043a-extirq"); domain = irq_domain_add_hierarchy(parent_domain, 0, priv->nirq, node, &extirq_domain_ops, priv); - if (!domain) + if (!domain) { ret = -ENOMEM; + goto err_add_hierarchy; + } -out: - if (ret) - kfree(priv); + return 0; + +err_add_hierarchy: +err_parse_map: + regmap_exit(priv->regmap); +err_regmap_init: + iounmap(base); +err_iomap: + kfree(priv); +err_alloc_priv: +err_irq_find_host: return ret; } -- 2.34.1
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