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Date: Fri, 7 Dec 2018 13:44:52 -0700
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Mike Leach <mike.leach@...aro.org>
Cc: linux@...linux.org.uk, coresight@...ts.linaro.org,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
suzuki.poulose@....com
Subject: Re: [PATCH v3 1/2] drivers: amba: Updates to component
identification for driver matching.
Good day Mike,
On Thu, Dec 06, 2018 at 12:02:25AM +0000, Mike Leach wrote:
> The CoreSight specification (ARM IHI 0029E), updates the ID register
> requirements for components on an AMBA bus, to cover both traditional
> ARM Primecell type devices, and newer CoreSight and other components.
>
> The Peripheral ID (PID) / Component ID (CID) pair is extended in certain
> cases to uniquely identify components. CoreSight components related to
> a single function can share Peripheral ID values, and must be further
> identified using a Unique Component Identifier (UCI). e.g. the ETM, CTI,
> PMU and Debug hardware of the A35 all share the same PID.
>
> Bits 15:12 of the CID are defined to be the device class.
> Class 0xF remains for PrimeCell and legacy components.
> Class 0x9 defines the component as CoreSight (CORESIGHT_CID above)
> Class 0x0, 0x1, 0xB, 0xE define components that do not have driver support
> at present.
> Class 0x2-0x8,0xA and 0xD-0xD are presently reserved.
>
> The specification futher defines which classes of device use the standard
> CID/PID pair, and when additional ID registers are required.
>
> The patches provide an update of amba_device and matching code to handle
> the additional registers required for the Class 0x9 (CoreSight) UCI.
> The *data pointer in the amba_id is used by the driver to provide extended
> ID register values for matching.
>
> CoreSight components where PID/CID pair is currently sufficient for
> unique identification need not provide this additional information.
>
> Signed-off-by: Mike Leach <mike.leach@...aro.org>
I am good with this patch but can't take it until Russell gives me the thumbs
up. He may also decide to take it in his tree, in which case:
Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Russell, let me know that is the easiest for you.
Thanks,
Mathieu
> ---
> drivers/amba/bus.c | 45 +++++++++++++++++++++++++++++++++-------
> include/linux/amba/bus.h | 32 ++++++++++++++++++++++++++++
> 2 files changed, 69 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 41b706403ef7..524296a0eba0 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -26,19 +26,36 @@
>
> #define to_amba_driver(d) container_of(d, struct amba_driver, drv)
>
> -static const struct amba_id *
> -amba_lookup(const struct amba_id *table, struct amba_device *dev)
> +/* called on periphid match and class 0x9 coresight device. */
> +static int
> +amba_cs_uci_id_match(const struct amba_id *table, struct amba_device *dev)
> {
> int ret = 0;
> + struct amba_cs_uci_id *uci;
> +
> + uci = table->data;
>
> + /* no table data - return match on periphid */
> + if (!uci)
> + return 1;
> +
> + /* test against read devtype and masked devarch value */
> + ret = (dev->uci.devtype == uci->devtype) &&
> + ((dev->uci.devarch & uci->devarch_mask) == uci->devarch);
> + return ret;
> +}
> +
> +static const struct amba_id *
> +amba_lookup(const struct amba_id *table, struct amba_device *dev)
> +{
> while (table->mask) {
> - ret = (dev->periphid & table->mask) == table->id;
> - if (ret)
> - break;
> + if (((dev->periphid & table->mask) == table->id) &&
> + ((dev->cid != CORESIGHT_CID) ||
> + (amba_cs_uci_id_match(table, dev))))
> + return table;
> table++;
> }
> -
> - return ret ? table : NULL;
> + return NULL;
> }
>
> static int amba_match(struct device *dev, struct device_driver *drv)
> @@ -399,10 +416,22 @@ static int amba_device_try_add(struct amba_device *dev, struct resource *parent)
> cid |= (readl(tmp + size - 0x10 + 4 * i) & 255) <<
> (i * 8);
>
> + if (cid == CORESIGHT_CID) {
> + /* set the base to the start of the last 4k block */
> + void __iomem *csbase = tmp + size - 4096;
> +
> + dev->uci.devarch =
> + readl(csbase + UCI_REG_DEVARCH_OFFSET);
> + dev->uci.devtype =
> + readl(csbase + UCI_REG_DEVTYPE_OFFSET) & 0xff;
> + }
> +
> amba_put_disable_pclk(dev);
>
> - if (cid == AMBA_CID || cid == CORESIGHT_CID)
> + if (cid == AMBA_CID || cid == CORESIGHT_CID) {
> dev->periphid = pid;
> + dev->cid = cid;
> + }
>
> if (!dev->periphid)
> ret = -ENODEV;
> diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
> index d143c13bed26..8c0f392e4da2 100644
> --- a/include/linux/amba/bus.h
> +++ b/include/linux/amba/bus.h
> @@ -25,6 +25,36 @@
> #define AMBA_CID 0xb105f00d
> #define CORESIGHT_CID 0xb105900d
>
> +/*
> + * CoreSight Architecture specification updates the ID specification
> + * for components on the AMBA bus. (ARM IHI 0029E)
> + *
> + * Bits 15:12 of the CID are the device class.
> + *
> + * Class 0xF remains for PrimeCell and legacy components. (AMBA_CID above)
> + * Class 0x9 defines the component as CoreSight (CORESIGHT_CID above)
> + * Class 0x0, 0x1, 0xB, 0xE define components that do not have driver support
> + * at present.
> + * Class 0x2-0x8,0xA and 0xD-0xD are presently reserved.
> + *
> + * Remaining CID bits stay as 0xb105-00d
> + */
> +
> +/*
> + * Class 0x9 components use additional values to form a Unique Component
> + * Identifier (UCI), where peripheral ID values are identical for different
> + * components. Passed to the amba bus code from the component driver via
> + * the amba_id->data pointer.
> + */
> +struct amba_cs_uci_id {
> + unsigned int devarch;
> + unsigned int devarch_mask;
> + unsigned int devtype;
> +};
> +
> +#define UCI_REG_DEVTYPE_OFFSET 0xFCC
> +#define UCI_REG_DEVARCH_OFFSET 0xFBC
> +
> struct clk;
>
> struct amba_device {
> @@ -32,6 +62,8 @@ struct amba_device {
> struct resource res;
> struct clk *pclk;
> unsigned int periphid;
> + unsigned int cid;
> + struct amba_cs_uci_id uci;
> unsigned int irq[AMBA_NR_IRQS];
> char *driver_override;
> };
> --
> 2.19.1
>
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