[PATCH 10/17] irqchip/irq-mvebu-sei: add new driver for Marvell SEI

Thomas Petazzoni
2018-05-02T09:17:44Z

Hello,

On Sat, 21 Apr 2018 15:55:30 +0200, Miquel Raynal wrote:

> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile
> index 5ed465ab1c76..6b5b75cb4694 100644
> --- a/drivers/irqchip/Makefile
> +++ b/drivers/irqchip/Makefile
> @@ -73,6 +73,7 @@ obj-$(CONFIG_IMX_GPCV2) += irq-imx-gpcv2.o
> obj-$(CONFIG_PIC32_EVIC) += irq-pic32-evic.o
> obj-$(CONFIG_MSCC_OCELOT_IRQ) += irq-mscc-ocelot.o
> obj-$(CONFIG_MVEBU_GICP) += irq-mvebu-gicp.o
> +obj-$(CONFIG_MVEBU_SEI) += irq-mvebu-sei.o
> obj-$(CONFIG_MVEBU_ICU) += irq-mvebu-icu.o
> obj-$(CONFIG_MVEBU_ODMI) += irq-mvebu-odmi.o
> obj-$(CONFIG_MVEBU_PIC) += irq-mvebu-pic.o

Alphabetic ordering would put SEI after PIC I guess :)

> diff --git a/drivers/irqchip/irq-mvebu-sei.c b/drivers/irqchip/irq-mvebu-sei.c
> new file mode 100644
> index 000000000000..5c12c74e3f09
> --- /dev/null
> +++ b/drivers/irqchip/irq-mvebu-sei.c
> @@ -0,0 +1,449 @@
> +// SPDX-License-Identifier: GPL-2.0 OR X11

License for code is GPL-2.0 only. We use GPL-2.0 OR X11 for Device
Trees.

> +#define pr_fmt(fmt) "mvebu-sei: " fmt
> +
> +#include <linux/irq.h>
> +#include <linux/interrupt.h>
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
> +#include <linux/kernel.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_platform.h>
> +#include <linux/msi.h>
> +#include <linux/platform_device.h>
> +#include <linux/irqchip.h>
> +
> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> +
> +#define GICP_SET_SEI_OFFSET 0x30
> +#define GICP_CLR_SEI_OFFSET GICP_SET_SEI_OFFSET

Why do you have this concept of set/clr if there is only one register ?
I assume that if there is only a "set" register, it means that SEI
interrupts can only be edge triggered, contrary to NSR interrupts,
which have separate set/clr to support level-triggered interrupts.

Having only a "set" offset means that we can rely on the existing
"struct msi_msg" to convey both the MSI doorbell address and payload,
and we don't need the mvebu_gicp_get_doorbells() hack.

> +/* Cause register */
> +#define GICP_SECR(idx) (0x0 + (idx * 0x4))
> +/* Mask register */
> +#define GICP_SEMR(idx) (0x20 + (idx * 0x4))

Minor nit: order register definitions by order of increasing offset,
i.e the GICP_SET_SEI_OFFSET should be defined here.

> +#define SEI_IRQ_NB_PER_REG 32
> +#define SEI_IRQ_REG_NB 2

s/NB/COUNT/

> +#define SEI_IRQ_NB (SEI_IRQ_NB_PER_REG * SEI_IRQ_REG_NB)

Ditto.

> +#define SEI_IRQ_REG_IDX(irq_id) (irq_id / SEI_IRQ_NB_PER_REG)
> +#define SEI_IRQ_REG_BIT(irq_id) (irq_id % SEI_IRQ_NB_PER_REG)
> +
> +struct mvebu_sei_interrupt_range {
> + u32 first;
> + u32 number;
> +};
> +
> +struct mvebu_sei {
> + struct device *dev;
> + void __iomem *base;
> + struct resource *res;
> + struct irq_domain *ap_domain;
> + struct irq_domain *cp_domain;
> + struct mvebu_sei_interrupt_range ap_interrupts;
> + struct mvebu_sei_interrupt_range cp_interrupts;
> + /* Lock on MSI allocations/releases */
> + spinlock_t cp_msi_lock;
> + DECLARE_BITMAP(cp_msi_bitmap, SEI_IRQ_NB);
> +};
> +
> +static int mvebu_sei_domain_to_sei_irq(struct mvebu_sei *sei,
> + struct irq_domain *domain,
> + irq_hw_number_t hwirq)
> +{
> + if (domain == sei->ap_domain)
> + return sei->ap_interrupts.first + hwirq;
> + else
> + return sei->cp_interrupts.first + hwirq;

I am not entirely clear whether we need subnodes or not in this
binding, but I guess we do because we have one subset of the interrupts
that are wired interrupts, and another part that are MSI triggered.

Perhaps this is one aspect on which Marc Zyngier can comment ?

> +static void mvebu_sei_reset(struct mvebu_sei *sei)
> +{
> + u32 reg_idx;
> +
> + for (reg_idx = 0; reg_idx < SEI_IRQ_REG_NB; reg_idx++) {
> + /* Clear all cause bits */
> + writel(0xFFFFFFFF, sei->base + GICP_SECR(reg_idx));
> + /* Enable all interrupts */
> + writel(0, sei->base + GICP_SEMR(reg_idx));

Enabling interrupts by default ? This looks weird. They should only be
enabled... when enabled.

> +int mvebu_sei_get_doorbells(struct device_node *dn, phys_addr_t *set,
> + phys_addr_t *clr)
> +{
> + struct platform_device *pdev;
> + struct mvebu_sei *sei;
> +
> + pdev = of_find_device_by_node(dn->parent);
> + if (!pdev)
> + return -ENODEV;
> +
> + sei = platform_get_drvdata(pdev);
> + if (!sei)
> + return -ENODEV;
> +
> + *set = (phys_addr_t)(sei->res->start + GICP_SET_SEI_OFFSET);
> + *clr = (phys_addr_t)(sei->res->start + GICP_CLR_SEI_OFFSET);
> +
> + return 0;
> +}

As I said above, I believe this hack is not needed, because SEIs are
edge-triggered, and we have a single SET_SEI_OFFSET MSI doorbell
address to convey, which makes "struct msi_msg" as it is today
sufficient.

> +static void mvebu_sei_mask_irq(struct irq_data *d)
> +{
> + struct mvebu_sei *sei = irq_data_get_irq_chip_data(d);
> + u32 reg_idx = SEI_IRQ_REG_IDX(d->hwirq);

This doesn't look right. The d->hwirq is relative to the beginning of
the domain, while you should use sei_irq here. For example, the SEI
n?32 (first interrupt in the second register) will have d->hwirq = 11,
because it is the 11th SEI interrupt for the CP. So here, you will
conclude that reg_idx = 0, while it should be reg_idx = 1.

> + u32 sei_irq = mvebu_sei_domain_to_sei_irq(sei, d->domain, d->hwirq);
> + u32 irq_mask = BIT(SEI_IRQ_REG_BIT(sei_irq));
> + u32 reg;
> +
> + /* 1 disables the interrupt */
> + reg = readl(sei->base + GICP_SEMR(reg_idx));
> + writel(reg | irq_mask, sei->base + GICP_SEMR(reg_idx));

Personal taste here, but I prefer:

reg = readl(sei->base + GICP_SEMR(reg_idx));
reg |= BIT(SEI_IRQ_REG_BIT(sei_irq));
writel(reg, sei->base + GICP_SEMR(reg_idx));

> +static void mvebu_sei_unmask_irq(struct irq_data *d)
> +{
> + struct mvebu_sei *sei = irq_data_get_irq_chip_data(d);
> + u32 reg_idx = SEI_IRQ_REG_IDX(d->hwirq);

Same mistake as above I believe.

> + u32 sei_irq = mvebu_sei_domain_to_sei_irq(sei, d->domain, d->hwirq);
> + u32 irq_mask = BIT(SEI_IRQ_REG_BIT(sei_irq));
> + u32 reg;
> +
> + /* 0 enables the interrupt */
> + reg = readl(sei->base + GICP_SEMR(reg_idx));
> + writel(reg & ~irq_mask, sei->base + GICP_SEMR(reg_idx));

And same nitpick comment :-)

> +static int mvebu_sei_irq_domain_alloc(struct irq_domain *domain,
> + unsigned int virq, unsigned int nr_irqs,
> + void *args)

I think the coding style says that arguments should be aligned, no ?

> +{
> + struct mvebu_sei *sei = domain->host_data;
> + struct irq_fwspec *fwspec = args;
> + struct irq_chip *irq_chip;
> + int sei_hwirq, hwirq;
> + int ret;
> +
> + /* Software only supports single allocations for now */
> + if (nr_irqs != 1)
> + return -ENOTSUPP;
> +
> + if (domain == sei->ap_domain) {
> + irq_chip = &mvebu_sei_ap_wired_irq_chip;
> + hwirq = fwspec->param[0];
> + } else {
> + irq_chip = &mvebu_sei_cp_msi_irq_chip;
> + spin_lock(&sei->cp_msi_lock);
> + hwirq = bitmap_find_free_region(sei->cp_msi_bitmap, SEI_IRQ_NB,
> + 0);
> + spin_unlock(&sei->cp_msi_lock);
> + if (hwirq < 0)
> + return -ENOSPC;
> + }
> +
> + sei_hwirq = mvebu_sei_domain_to_sei_irq(sei, domain, hwirq);
> +
> + fwspec->fwnode = domain->parent->fwnode;
> + fwspec->param_count = 3;
> + fwspec->param[0] = GIC_SPI;
> + fwspec->param[1] = sei_hwirq;
> + fwspec->param[2] = IRQ_TYPE_EDGE_RISING;

Maybe it's me being confused, but I thought all SEI interrupts were
muxed together to a single SPI for the parent GIC. But here, you
allocate different SPIs at the GIC level. Intuitively, this doesn't
look good. Haven't you copy/pasted too much from the gicp driver, where
we have a 1:1 mapping between interrupts coming into the GICP and
interrupts signaled by the GICP to the GIC, while here we have a N:1
mapping, with N interrupts coming into the GICP_SEI, and only one
interrupt leaving the GICP_SEI to the GIC ?

> +static const struct irq_domain_ops mvebu_sei_ap_domain_ops = {
> + .xlate = irq_domain_xlate_onecell,
> + .alloc = mvebu_sei_irq_domain_alloc,
> + .free = mvebu_sei_irq_domain_free,
> +};
> +
> +static const struct irq_domain_ops mvebu_sei_cp_domain_ops = {
> + .xlate = irq_domain_xlate_twocell,
> + .alloc = mvebu_sei_irq_domain_alloc,
> + .free = mvebu_sei_irq_domain_free,
> +};

Why do you need two cells for the interrupts coming from the CP and
only one cell for the interrupts coming from the AP ?

For thermal in the AP, you do:

+ interrupt-parent = <&sei_wired_controller>;
+ interrupts = <18>;

i.e, you don't specify an interrupt type. For thermal in the CP, you do:

+ interrupts-extended =
+ <&CP110_LABEL(icu_sei) 116 IRQ_TYPE_LEVEL_HIGH>;

here you specify an interrupt type. I'm not sure why you have this
difference. Even more so because I think a SEI level interrupt is not
possible, since you only have a "SET" register and no "CLR" register.

Some guidance from Marc here might be useful perhaps.

> +static int mvebu_sei_probe(struct platform_device *pdev)
> +{
> + struct device_node *node = pdev->dev.of_node, *parent, *child;
> + struct irq_domain *parent_domain, *plat_domain;
> + struct mvebu_sei *sei;
> + const __be32 *property;
> + u32 top_level_spi, size;
> + int ret;
> +
> + sei = devm_kzalloc(&pdev->dev, sizeof(*sei), GFP_KERNEL);
> + if (!sei)
> + return -ENOMEM;
> +
> + sei->dev = &pdev->dev;
> +
> + spin_lock_init(&sei->cp_msi_lock);
> +
> + sei->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!sei->res) {
> + dev_err(sei->dev, "Failed to retrieve SEI resource\n");
> + return -ENODEV;
> + }
> +
> + sei->base = devm_ioremap(sei->dev, sei->res->start,
> + resource_size(sei->res));
> + if (!sei->base) {
> + dev_err(sei->dev, "Failed to remap SEI resource\n");
> + return -ENODEV;
> + }

Use devm_ioremap_resource() here, and remove the error handling of
platform_get_resource(), because it's already taken care of by
devm_ioremap_resource().

> + /*
> + * Reserve the single (top-level) parent SPI IRQ from which all the
> + * interrupts handled by this driver will be signaled.
> + */
> + top_level_spi = irq_of_parse_and_map(node, 0);
> + if (top_level_spi <= 0) {
> + dev_err(sei->dev, "Failed to retrieve top-level SPI IRQ\n");
> + return -ENODEV;
> + }

Rather than top_level_spi, something like parent_irq would make more
sense to me.

> + irq_set_chained_handler(top_level_spi, mvebu_sei_handle_cascade_irq);
> + irq_set_handler_data(top_level_spi, sei);
> +
> + /*
> + * SEIs in the range [ 0; 20] are wired and come from the AP.
> + * SEIs in the range [21; 63] are CP SEI and are triggered through MSIs.
> + *
> + * Each SEI 'domain' is represented as a subnode.
> + */
> +
> + /* Get a reference to the parent domain to create a hierarchy */
> + parent = of_irq_find_parent(node);
> + if (!parent) {
> + dev_err(sei->dev, "Failed to find parent IRQ node\n");
> + ret = -ENODEV;
> + goto dispose_irq;
> + }
> +
> + parent_domain = irq_find_host(parent);
> + if (!parent_domain) {
> + dev_err(sei->dev, "Failed to find parent IRQ domain\n");
> + ret = -ENODEV;
> + goto dispose_irq;
> + }
> +
> + /* Create the 'wired' hierarchy */
> + child = of_find_node_by_name(node, "sei-wired-controller");
> + if (!child) {
> + dev_err(sei->dev, "Missing 'sei-wired-controller' subnode\n");
> + ret = -ENODEV;
> + goto dispose_irq;
> + }

Don't forget to of_node_put(child) once you're done using this DT node
reference.

> +
> + property = of_get_property(child, "reg", &size);
> + if (!property || size != (2 * sizeof(u32))) {
> + dev_err(sei->dev, "Missing subnode 'reg' property\n");
> + ret = -ENODEV;
> + goto dispose_irq;
> + }

As Rob said, I don't think the "reg" property is appropriate for this
usage.

> + sei->ap_interrupts.first = be32_to_cpu(property[0]);
> + sei->ap_interrupts.number = be32_to_cpu(property[1]);
> + sei->ap_domain = irq_domain_create_hierarchy(parent_domain, 0,
> + sei->ap_interrupts.number,
> + of_node_to_fwnode(child),
> + &mvebu_sei_ap_domain_ops,
> + sei);
> + if (!sei->ap_domain) {
> + dev_err(sei->dev, "Failed to create AP IRQ domain\n");
> + ret = -ENOMEM;
> + goto dispose_irq;
> + }
> +
> + /* Create the 'MSI' hierarchy */
> + child = of_find_node_by_name(node, "sei-msi-controller");
> + if (!child) {
> + dev_err(sei->dev, "Missing 'sei-msi-controller' subnode\n");
> + ret = -ENODEV;
> + goto remove_ap_domain;
> + }

Ditto: missing of_node_put(child) somewhere below to balance
of_find_node_by_name().

> + property = of_get_property(child, "reg", &size);
> + if (!property || size != (2 * sizeof(u32))) {
> + dev_err(sei->dev, "Missing subnode 'reg' property\n");
> + ret = -ENODEV;
> + goto remove_ap_domain;
> + }
> +
> + sei->cp_interrupts.first = be32_to_cpu(property[0]);
> + sei->cp_interrupts.number = be32_to_cpu(property[1]);
> + sei->cp_domain = irq_domain_create_hierarchy(parent_domain, 0,
> + sei->cp_interrupts.number,
> + of_node_to_fwnode(child),
> + &mvebu_sei_cp_domain_ops,
> + sei);
> + if (!sei->cp_domain) {
> + pr_err("Failed to create CPs IRQ domain\n");
> + ret = -ENOMEM;
> + goto remove_ap_domain;
> + }
> +
> + plat_domain = platform_msi_create_irq_domain(of_node_to_fwnode(child),
> + &mvebu_sei_msi_domain_info,
> + sei->cp_domain);
> + if (!plat_domain) {
> + pr_err("Failed to create CPs MSI domain\n");
> + ret = -ENOMEM;
> + goto remove_cp_domain;
> + }

> +
> + platform_set_drvdata(pdev, sei);
> +
> + mvebu_sei_reset(sei);

Please do the reset *before* registering the IRQ domains, it's more
logical to have the HW ready and then expose it to Linux rather than
the opposite.

It would be nice to have the review from Marc on this driver,
especially on whether the SEI is properly modeled in terms of IRQ
domains;

> diff --git a/drivers/irqchip/irq-mvebu-sei.h b/drivers/irqchip/irq-mvebu-sei.h
> new file mode 100644
> index 000000000000..f0c12a441923
> --- /dev/null
> +++ b/drivers/irqchip/irq-mvebu-sei.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __MVEBU_SEI_H__
> +#define __MVEBU_SEI_H__
> +
> +#include <linux/types.h>
> +
> +struct device_node;
> +
> +int mvebu_sei_get_doorbells(struct device_node *dn, phys_addr_t *set,
> + phys_addr_t *clr);
> +
> +#endif /* __MVEBU_SEI_H__ */

This header file can be removed if you drop mvebu_sei_get_doorbells(),
as suggested above.

Best regards,

Thomas
--
Thomas Petazzoni, CTO, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering