Re: [PATCH] drivers: mailbox: handle SGI for shared IPI

[Tanmay Shah]

Hello,

Ping for reviews.

Thanks,
Tanmay

On 5/3/24 9:15 AM, Tanmay Shah wrote:
> At least one IPI is used in TF-A for communication with PMC firmware.
> If this IPI needs to be used by other agents such as RPU then, IPI
> system interrupt can't be generated in mailbox driver. In such case
> TF-A generates SGI to mailbox driver for IPI notification.
> 
> Signed-off-by: Tanmay Shah <tanmay.shah@xxxxxxx>
> Signed-off-by: Saeed Nowshadi <saeed.nowshadi@xxxxxxx>
> ---
>  drivers/mailbox/zynqmp-ipi-mailbox.c | 159 +++++++++++++++++++++++++--
>  1 file changed, 152 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mailbox/zynqmp-ipi-mailbox.c b/drivers/mailbox/zynqmp-ipi-mailbox.c
> index 1cb553cced90..7c90bac3de21 100644
> --- a/drivers/mailbox/zynqmp-ipi-mailbox.c
> +++ b/drivers/mailbox/zynqmp-ipi-mailbox.c
> @@ -6,9 +6,11 @@
>   */
>  
>  #include <linux/arm-smccc.h>
> +#include <linux/cpuhotplug.h>
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/interrupt.h>
> +#include <linux/irqdomain.h>
>  #include <linux/io.h>
>  #include <linux/kernel.h>
>  #include <linux/mailbox_controller.h>
> @@ -16,6 +18,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_address.h>
> +#include <linux/of_irq.h>
>  #include <linux/platform_device.h>
>  
>  /* IPI agent ID any */
> @@ -59,6 +62,8 @@
>  #define DST_BIT_POS	9U
>  #define SRC_BITMASK	GENMASK(11, 8)
>  
> +#define MAX_SGI 16
> +
>  /**
>   * struct zynqmp_ipi_mchan - Description of a Xilinx ZynqMP IPI mailbox channel
>   * @is_opened: indicate if the IPI channel is opened
> @@ -111,6 +116,7 @@ struct zynqmp_ipi_mbox {
>   * @irq:                  IPI agent interrupt ID
>   * @method:               IPI SMC or HVC is going to be used
>   * @local_id:             local IPI agent ID
> + * @virq_sgi:             IRQ number mapped to SGI
>   * @num_mboxes:           number of mailboxes of this IPI agent
>   * @ipi_mboxes:           IPI mailboxes of this IPI agent
>   */
> @@ -119,10 +125,13 @@ struct zynqmp_ipi_pdata {
>  	int irq;
>  	unsigned int method;
>  	u32 local_id;
> +	int virq_sgi;
>  	int num_mboxes;
>  	struct zynqmp_ipi_mbox ipi_mboxes[] __counted_by(num_mboxes);
>  };
>  
> +static DEFINE_PER_CPU(struct zynqmp_ipi_pdata *, per_cpu_pdata);
> +
>  static struct device_driver zynqmp_ipi_mbox_driver = {
>  	.owner = THIS_MODULE,
>  	.name = "zynqmp-ipi-mbox",
> @@ -189,6 +198,14 @@ static irqreturn_t zynqmp_ipi_interrupt(int irq, void *data)
>  	return status;
>  }
>  
> +static irqreturn_t zynqmp_sgi_interrupt(int irq, void *data)
> +{
> +	struct zynqmp_ipi_pdata **pdata_ptr = data;
> +	struct zynqmp_ipi_pdata *pdata = *pdata_ptr;
> +
> +	return zynqmp_ipi_interrupt(irq, pdata);
> +}
> +
>  /**
>   * zynqmp_ipi_peek_data - Peek to see if there are any rx messages.
>   *
> @@ -748,6 +765,112 @@ static int versal_ipi_setup(struct zynqmp_ipi_mbox *ipi_mbox,
>  	return 0;
>  }
>  
> +static int xlnx_mbox_cpuhp_start(unsigned int cpu)
> +{
> +	struct zynqmp_ipi_pdata *pdata;
> +
> +	pdata = get_cpu_var(per_cpu_pdata);
> +	put_cpu_var(per_cpu_pdata);
> +	enable_percpu_irq(pdata->virq_sgi, IRQ_TYPE_NONE);
> +
> +	return 0;
> +}
> +
> +static int xlnx_mbox_cpuhp_down(unsigned int cpu)
> +{
> +	struct zynqmp_ipi_pdata *pdata;
> +
> +	pdata = get_cpu_var(per_cpu_pdata);
> +	put_cpu_var(per_cpu_pdata);
> +	disable_percpu_irq(pdata->virq_sgi);
> +
> +	return 0;
> +}
> +
> +static void xlnx_disable_percpu_irq(void *data)
> +{
> +	struct zynqmp_ipi_pdata *pdata;
> +
> +	pdata = *this_cpu_ptr(&per_cpu_pdata);
> +
> +	disable_percpu_irq(pdata->virq_sgi);
> +}
> +
> +static int xlnx_mbox_init_sgi(struct platform_device *pdev,
> +			      int sgi_num,
> +			      struct zynqmp_ipi_pdata *pdata)
> +{
> +	int ret = 0;
> +	int cpu;
> +
> +	/*
> +	 * IRQ related structures are used for the following:
> +	 * for each SGI interrupt ensure its mapped by GIC IRQ domain
> +	 * and that each corresponding linux IRQ for the HW IRQ has
> +	 * a handler for when receiving an interrupt from the remote
> +	 * processor.
> +	 */
> +	struct irq_domain *domain;
> +	struct irq_fwspec sgi_fwspec;
> +	struct device_node *interrupt_parent = NULL;
> +	struct device *dev = &pdev->dev;
> +
> +	/* Find GIC controller to map SGIs. */
> +	interrupt_parent = of_irq_find_parent(dev->of_node);
> +	if (!interrupt_parent) {
> +		dev_err(&pdev->dev, "Failed to find property for Interrupt parent\n");
> +		return -EINVAL;
> +	}
> +
> +	/* Each SGI needs to be associated with GIC's IRQ domain. */
> +	domain = irq_find_host(interrupt_parent);
> +	of_node_put(interrupt_parent);
> +
> +	/* Each mapping needs GIC domain when finding IRQ mapping. */
> +	sgi_fwspec.fwnode = domain->fwnode;
> +
> +	/*
> +	 * When irq domain looks at mapping each arg is as follows:
> +	 * 3 args for: interrupt type (SGI), interrupt # (set later), type
> +	 */
> +	sgi_fwspec.param_count = 1;
> +
> +	/* Set SGI's hwirq */
> +	sgi_fwspec.param[0] = sgi_num;
> +	pdata->virq_sgi = irq_create_fwspec_mapping(&sgi_fwspec);
> +
> +	for_each_possible_cpu(cpu)
> +		per_cpu(per_cpu_pdata, cpu) = pdata;
> +
> +	ret = request_percpu_irq(pdata->virq_sgi, zynqmp_sgi_interrupt, pdev->name,
> +				 &per_cpu_pdata);
> +	WARN_ON(ret);
> +	if (ret) {
> +		irq_dispose_mapping(pdata->virq_sgi);
> +		return ret;
> +	}
> +
> +	irq_to_desc(pdata->virq_sgi);
> +	irq_set_status_flags(pdata->virq_sgi, IRQ_PER_CPU);
> +
> +	/* Setup function for the CPU hot-plug cases */
> +	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mailbox/sgi:starting",
> +			  xlnx_mbox_cpuhp_start, xlnx_mbox_cpuhp_down);
> +
> +	return ret;
> +}
> +
> +static void xlnx_mbox_cleanup_sgi(struct zynqmp_ipi_pdata *pdata)
> +{
> +	cpuhp_remove_state(CPUHP_AP_ONLINE_DYN);
> +
> +	on_each_cpu(xlnx_disable_percpu_irq, NULL, 1);
> +
> +	irq_clear_status_flags(pdata->virq_sgi, IRQ_PER_CPU);
> +	free_percpu_irq(pdata->virq_sgi, &per_cpu_pdata);
> +	irq_dispose_mapping(pdata->virq_sgi);
> +}
> +
>  /**
>   * zynqmp_ipi_free_mboxes - Free IPI mailboxes devices
>   *
> @@ -758,6 +881,9 @@ static void zynqmp_ipi_free_mboxes(struct zynqmp_ipi_pdata *pdata)
>  	struct zynqmp_ipi_mbox *ipi_mbox;
>  	int i;
>  
> +	if (pdata->irq < MAX_SGI)
> +		xlnx_mbox_cleanup_sgi(pdata);
> +
>  	i = pdata->num_mboxes;
>  	for (; i >= 0; i--) {
>  		ipi_mbox = &pdata->ipi_mboxes[i];
> @@ -773,7 +899,8 @@ static int zynqmp_ipi_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
>  	struct device_node *nc, *np = pdev->dev.of_node;
> -	struct zynqmp_ipi_pdata *pdata;
> +	struct zynqmp_ipi_pdata __percpu *pdata;
> +	struct of_phandle_args out_irq;
>  	struct zynqmp_ipi_mbox *mbox;
>  	int num_mboxes, ret = -EINVAL;
>  	setup_ipi_fn ipi_fn;
> @@ -821,14 +948,32 @@ static int zynqmp_ipi_probe(struct platform_device *pdev)
>  		mbox++;
>  	}
>  
> -	/* IPI IRQ */
> -	ret = platform_get_irq(pdev, 0);
> -	if (ret < 0)
> +	ret = of_irq_parse_one(dev_of_node(dev), 0, &out_irq);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to parse interrupts\n");
>  		goto free_mbox_dev;
> +	}
> +	ret = out_irq.args[1];
> +
> +	/*
> +	 * If Interrupt number is in SGI range, then request SGI else request
> +	 * IPI system IRQ.
> +	 */
> +	if (ret < MAX_SGI) {
> +		pdata->irq = ret;
> +		ret = xlnx_mbox_init_sgi(pdev, pdata->irq, pdata);
> +		if (ret)
> +			goto free_mbox_dev;
> +	} else {
> +		ret = platform_get_irq(pdev, 0);
> +		if (ret < 0)
> +			goto free_mbox_dev;
> +
> +		pdata->irq = ret;
> +		ret = devm_request_irq(dev, pdata->irq, zynqmp_ipi_interrupt,
> +				       IRQF_SHARED, dev_name(dev), pdata);
> +	}
>  
> -	pdata->irq = ret;
> -	ret = devm_request_irq(dev, pdata->irq, zynqmp_ipi_interrupt,
> -			       IRQF_SHARED, dev_name(dev), pdata);
>  	if (ret) {
>  		dev_err(dev, "IRQ %d is not requested successfully.\n",
>  			pdata->irq);
> 
> base-commit: 9221b2819b8a4196eecf5476d66201be60fbcf29