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[PATCH v2 4/5] irqchip:create irq domain for each mbigen device

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  [PATCH v2 4/5] irqchip:create irq domain for each mbigen device MaJun <majun258@huawei.com> - 2016-02-16 07:40 +0100
    Re: [PATCH v2 4/5] irqchip:create irq domain for each mbigen device Marc Zyngier <marc.zyngier@arm.com> - 2016-02-16 10:00 +0100
      Re: [PATCH v2 4/5] irqchip:create irq domain for each mbigen device "majun (F)" <majun258@huawei.com> - 2016-02-17 05:30 +0100
        Re: [PATCH v2 4/5] irqchip:create irq domain for each mbigen device Marc Zyngier <marc.zyngier@arm.com> - 2016-02-17 08:50 +0100

#1335074 — [PATCH v2 4/5] irqchip:create irq domain for each mbigen device

From: Ma Jun <majun258@huawei.com>

For peripheral devices which connect to mbigen,mbigen is a interrupt
controller. So, we create irq domain for each mbigen device and add
mbigen irq domain into irq hierarchy structure.

Signed-off-by: Ma Jun <majun258@huawei.com>
---
 drivers/irqchip/irq-mbigen-v1.c |  136 +++++++++++++++++++++++++++++++++++++++
 1 files changed, 136 insertions(+), 0 deletions(-)

diff --git a/drivers/irqchip/irq-mbigen-v1.c b/drivers/irqchip/irq-mbigen-v1.c
index 9445658..61e7ad0 100644
--- a/drivers/irqchip/irq-mbigen-v1.c
+++ b/drivers/irqchip/irq-mbigen-v1.c
@@ -16,11 +16,30 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/interrupt.h>
+#include <linux/irqchip.h>
 #include <linux/module.h>
+#include <linux/msi.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
+/* The maximum IRQ pin number of mbigen chip(start from 0) */
+#define MAXIMUM_IRQ_PIN_NUM		640
+
+/**
+ * In mbigen vector register
+ * bit[31:16]:	device id
+ * bit[15:0]:	event id value
+ */
+#define IRQ_EVENT_ID_MASK		0xffff
+
+/* offset of vector register in mbigen node */
+#define REG_MBIGEN_VEC_OFFSET		0x300
+#define REG_MBIGEN_EXT_VEC_OFFSET		0x320
+
 /**
  * struct mbigen_device - holds the information of mbigen device.
  *
@@ -32,10 +51,112 @@ struct mbigen_device {
 	void __iomem		*base;
 };
 
+static int get_mbigen_nid(unsigned int offset)
+{
+	int nid = 0;
+
+	if (offset < 256)
+		nid = offset / 64;
+	else if (offset < 384)
+		nid = 4;
+	else if (offset < 640)
+		nid = 5;
+
+	return nid;
+}
+
+static inline unsigned int get_mbigen_vec_reg(irq_hw_number_t hwirq)
+{
+	unsigned int nid;
+
+	nid = get_mbigen_nid(hwirq);
+
+	if (nid < 4)
+		return (nid * 4) + REG_MBIGEN_VEC_OFFSET;
+	else
+		return (nid - 4) * 4 + REG_MBIGEN_EXT_VEC_OFFSET;
+}
+
+static struct irq_chip mbigen_irq_chip = {
+	.name =			"mbigen-v1",
+};
+
+static void mbigen_write_msg(struct msi_desc *desc, struct msi_msg *msg)
+{
+	/* The address of doorbell is encoded in mbigen register by default
+	 * So,we don't need to program the doorbell address at here
+	 * Besides, the event ID is decided by the hardware pin number,
+	 * we can't change it in software.So, we don't need to encode the
+	 * event ID in mbigen register.
+	 */
+}
+
+static int mbigen_domain_translate(struct irq_domain *d,
+				    struct irq_fwspec *fwspec,
+				    unsigned long *hwirq,
+				    unsigned int *type)
+{
+	if (is_of_node(fwspec->fwnode)) {
+		if (fwspec->param_count != 2)
+			return -EINVAL;
+
+		if (fwspec->param[0] > MAXIMUM_IRQ_PIN_NUM)
+			return -EINVAL;
+
+		*hwirq = fwspec->param[0];
+
+		/* If there is no valid irq type, just use the default type */
+		if ((fwspec->param[1] == IRQ_TYPE_EDGE_RISING) ||
+			(fwspec->param[1] == IRQ_TYPE_LEVEL_HIGH))
+			*type = fwspec->param[1];
+		else
+			return -EINVAL;
+
+		return 0;
+	}
+	return -EINVAL;
+}
+
+static int mbigen_irq_domain_alloc(struct irq_domain *domain,
+					unsigned int virq,
+					unsigned int nr_irqs,
+					void *args)
+{
+	struct irq_fwspec *fwspec = args;
+	irq_hw_number_t hwirq;
+	unsigned int type;
+	struct mbigen_device *mgn_chip;
+	int i, err;
+
+	err = mbigen_domain_translate(domain, fwspec, &hwirq, &type);
+	if (err)
+		return err;
+
+	err = platform_msi_domain_alloc(domain, virq, nr_irqs);
+	if (err)
+		return err;
+
+	mgn_chip = platform_msi_get_host_data(domain);
+
+	for (i = 0; i < nr_irqs; i++)
+		irq_domain_set_hwirq_and_chip(domain, virq + i, hwirq + i,
+				      &mbigen_irq_chip, mgn_chip->base);
+
+	return 0;
+}
+
+static struct irq_domain_ops mbigen_domain_ops = {
+	.translate	= mbigen_domain_translate,
+	.alloc		= mbigen_irq_domain_alloc,
+	.free		= irq_domain_free_irqs_common,
+};
+
 static int mbigen_device_probe(struct platform_device *pdev)
 {
 	struct mbigen_device *mgn_chip;
 	struct resource *res;
+	struct irq_domain *domain;
+	u32 num_pins;
 
 	mgn_chip = devm_kzalloc(&pdev->dev, sizeof(*mgn_chip), GFP_KERNEL);
 	if (!mgn_chip)
@@ -48,8 +169,23 @@ static int mbigen_device_probe(struct platform_device *pdev)
 	if (IS_ERR(mgn_chip->base))
 		return PTR_ERR(mgn_chip->base);
 
+	if (of_property_read_u32(pdev->dev.of_node, "num-pins", &num_pins) < 0) {
+		dev_err(&pdev->dev, "No num-pins property\n");
+		return -EINVAL;
+	}
+
+	domain = platform_msi_create_device_domain(&pdev->dev, num_pins,
+							mbigen_write_msg,
+							&mbigen_domain_ops,
+							mgn_chip);
+
+	if (!domain)
+		return -ENOMEM;
+
 	platform_set_drvdata(pdev, mgn_chip);
 
+	dev_info(&pdev->dev, "Allocated %d MSIs\n", num_pins);
+
 	return 0;
 }
 
-- 
1.7.1

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#1335171

On Tue, 16 Feb 2016 14:37:27 +0800
MaJun <majun258@huawei.com> wrote:

> From: Ma Jun <majun258@huawei.com>
> 
> For peripheral devices which connect to mbigen,mbigen is a interrupt
> controller. So, we create irq domain for each mbigen device and add
> mbigen irq domain into irq hierarchy structure.
> 
> Signed-off-by: Ma Jun <majun258@huawei.com>
> ---
>  drivers/irqchip/irq-mbigen-v1.c |  136 +++++++++++++++++++++++++++++++++++++++
>  1 files changed, 136 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-mbigen-v1.c b/drivers/irqchip/irq-mbigen-v1.c
> index 9445658..61e7ad0 100644
> --- a/drivers/irqchip/irq-mbigen-v1.c
> +++ b/drivers/irqchip/irq-mbigen-v1.c
> @@ -16,11 +16,30 @@
>   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
>   */
>  
> +#include <linux/interrupt.h>
> +#include <linux/irqchip.h>
>  #include <linux/module.h>
> +#include <linux/msi.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
>  
> +/* The maximum IRQ pin number of mbigen chip(start from 0) */
> +#define MAXIMUM_IRQ_PIN_NUM		640
> +
> +/**
> + * In mbigen vector register
> + * bit[31:16]:	device id
> + * bit[15:0]:	event id value
> + */
> +#define IRQ_EVENT_ID_MASK		0xffff
> +
> +/* offset of vector register in mbigen node */
> +#define REG_MBIGEN_VEC_OFFSET		0x300
> +#define REG_MBIGEN_EXT_VEC_OFFSET		0x320
> +
>  /**
>   * struct mbigen_device - holds the information of mbigen device.
>   *
> @@ -32,10 +51,112 @@ struct mbigen_device {
>  	void __iomem		*base;
>  };
>  
> +static int get_mbigen_nid(unsigned int offset)
> +{
> +	int nid = 0;
> +
> +	if (offset < 256)
> +		nid = offset / 64;
> +	else if (offset < 384)
> +		nid = 4;
> +	else if (offset < 640)
> +		nid = 5;
> +
> +	return nid;
> +}
> +
> +static inline unsigned int get_mbigen_vec_reg(irq_hw_number_t hwirq)
> +{
> +	unsigned int nid;
> +
> +	nid = get_mbigen_nid(hwirq);
> +
> +	if (nid < 4)
> +		return (nid * 4) + REG_MBIGEN_VEC_OFFSET;
> +	else
> +		return (nid - 4) * 4 + REG_MBIGEN_EXT_VEC_OFFSET;
> +}
> +
> +static struct irq_chip mbigen_irq_chip = {
> +	.name =			"mbigen-v1",
> +};
> +
> +static void mbigen_write_msg(struct msi_desc *desc, struct msi_msg *msg)
> +{
> +	/* The address of doorbell is encoded in mbigen register by default
> +	 * So,we don't need to program the doorbell address at here
> +	 * Besides, the event ID is decided by the hardware pin number,
> +	 * we can't change it in software.So, we don't need to encode the
> +	 * event ID in mbigen register.
> +	 */

Really? What if tomorrow I decide to change the EventID allocation
policy in the ITS driver? Have your HW engineers really baked the
behaviour of the Linux driver into the device?

I'm puzzled.

	M.
-- 
Jazz is not dead. It just smells funny.

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#1336051

在 2016/2/16 16:50, Marc Zyngier 写道:
> On Tue, 16 Feb 2016 14:37:27 +0800
> MaJun <majun258@huawei.com> wrote:
> 
>> From: Ma Jun <majun258@huawei.com>
[...]
>> +	unsigned int nid;
>> +
>> +	nid = get_mbigen_nid(hwirq);
>> +
>> +	if (nid < 4)
>> +		return (nid * 4) + REG_MBIGEN_VEC_OFFSET;
>> +	else
>> +		return (nid - 4) * 4 + REG_MBIGEN_EXT_VEC_OFFSET;
>> +}
>> +
>> +static struct irq_chip mbigen_irq_chip = {
>> +	.name =			"mbigen-v1",
>> +};
>> +
>> +static void mbigen_write_msg(struct msi_desc *desc, struct msi_msg *msg)
>> +{
>> +	/* The address of doorbell is encoded in mbigen register by default
>> +	 * So,we don't need to program the doorbell address at here
>> +	 * Besides, the event ID is decided by the hardware pin number,
>> +	 * we can't change it in software.So, we don't need to encode the
>> +	 * event ID in mbigen register.
>> +	 */
> 
> Really? What if tomorrow I decide to change the EventID allocation
> policy in the ITS driver? Have your HW engineers really baked the
> behaviour of the Linux driver into the device?
> 

Yes.
If we really need to support this chip,is there
any possible solution for this problem?

Thanks!
MaJun

> I'm puzzled.
> 
> 	M.
> 

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#1336114

On Wed, 17 Feb 2016 12:18:52 +0800
"majun (F)" <majun258@huawei.com> wrote:

> 
> 
> 在 2016/2/16 16:50, Marc Zyngier 写道:
> > On Tue, 16 Feb 2016 14:37:27 +0800
> > MaJun <majun258@huawei.com> wrote:
> > 
> >> From: Ma Jun <majun258@huawei.com>
> [...]
> >> +	unsigned int nid;
> >> +
> >> +	nid = get_mbigen_nid(hwirq);
> >> +
> >> +	if (nid < 4)
> >> +		return (nid * 4) + REG_MBIGEN_VEC_OFFSET;
> >> +	else
> >> +		return (nid - 4) * 4 + REG_MBIGEN_EXT_VEC_OFFSET;
> >> +}
> >> +
> >> +static struct irq_chip mbigen_irq_chip = {
> >> +	.name =			"mbigen-v1",
> >> +};
> >> +
> >> +static void mbigen_write_msg(struct msi_desc *desc, struct msi_msg *msg)
> >> +{
> >> +	/* The address of doorbell is encoded in mbigen register by default
> >> +	 * So,we don't need to program the doorbell address at here
> >> +	 * Besides, the event ID is decided by the hardware pin number,
> >> +	 * we can't change it in software.So, we don't need to encode the
> >> +	 * event ID in mbigen register.
> >> +	 */
> > 
> > Really? What if tomorrow I decide to change the EventID allocation
> > policy in the ITS driver? Have your HW engineers really baked the
> > behaviour of the Linux driver into the device?
> > 
> 
> Yes.
> If we really need to support this chip,is there
> any possible solution for this problem?

You would have to provide some sort of lookup table from the
device-tree, or find a way to pass this information down the ITS code.

The real question is: do we take this as it is and fix it once it
breaks? or do we mandate a proper solution before this has a remote
chance of getting in?

At the moment, I don't know, because the idea of hardcoded MSIs is so
wrong and so against the way the whole stack works that I just want to
say no to this and run away.

I need to think.

	M.
-- 
Jazz is not dead. It just smells funny.

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