Date:   Fri, 30 Aug 2019 15:57:16 +0300
From:   Peter Ujfalusi <peter.ujfalusi@...com>
To:     <vkoul@...nel.org>, <robh+dt@...nel.org>, <nm@...com>,
        <ssantosh@...nel.org>
CC:     <dan.j.williams@...el.com>, <dmaengine@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <grygorii.strashko@...com>, <lokeshvutla@...com>,
        <t-kristo@...com>, <tony@...mide.com>, <j-keerthy@...com>
Subject: Re: [PATCH v2 02/14] soc: ti: k3: add navss ringacc driver

Hi,

On 30/07/2019 12.34, Peter Ujfalusi wrote:
> From: Grygorii Strashko <grygorii.strashko@...com>
> 
> The Ring Accelerator (RINGACC or RA) provides hardware acceleration to
> enable straightforward passing of work between a producer and a consumer.
> There is one RINGACC module per NAVSS on TI AM65x SoCs.
> 
> The RINGACC converts constant-address read and write accesses to equivalent
> read or write accesses to a circular data structure in memory. The RINGACC
> eliminates the need for each DMA controller which needs to access ring
> elements from having to know the current state of the ring (base address,
> current offset). The DMA controller performs a read or write access to a
> specific address range (which maps to the source interface on the RINGACC)
> and the RINGACC replaces the address for the transaction with a new address
> which corresponds to the head or tail element of the ring (head for reads,
> tail for writes). Since the RINGACC maintains the state, multiple DMA
> controllers or channels are allowed to coherently share the same rings as
> applicable. The RINGACC is able to place data which is destined towards
> software into cached memory directly.
> 
> Supported ring modes:
> - Ring Mode
> - Messaging Mode
> - Credentials Mode
> - Queue Manager Mode
> 
> TI-SCI integration:
> 
> Texas Instrument's System Control Interface (TI-SCI) Message Protocol now
> has control over Ringacc module resources management (RM) and Rings
> configuration.
> 
> The corresponding support of TI-SCI Ringacc module RM protocol
> introduced as option through DT parameters:
> - ti,sci: phandle on TI-SCI firmware controller DT node
> - ti,sci-dev-id: TI-SCI device identifier as per TI-SCI firmware spec
> 
> if both parameters present - Ringacc driver will configure/free/reset Rings
> using TI-SCI Message Ringacc RM Protocol.
> 
> The Ringacc driver manages Rings allocation by itself now and requests
> TI-SCI firmware to allocate and configure specific Rings only. It's done
> this way because, Linux driver implements two stage Rings allocation and
> configuration (allocate ring and configure ring) while I-SCI Message
> Protocol supports only one combined operation (allocate+configure).
> 
> Grygorii Strashko <grygorii.strashko@...com>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
> ---
>  drivers/soc/ti/Kconfig            |   17 +
>  drivers/soc/ti/Makefile           |    1 +
>  drivers/soc/ti/k3-ringacc.c       | 1191 +++++++++++++++++++++++++++++
>  include/linux/soc/ti/k3-ringacc.h |  262 +++++++
>  4 files changed, 1471 insertions(+)
>  create mode 100644 drivers/soc/ti/k3-ringacc.c
>  create mode 100644 include/linux/soc/ti/k3-ringacc.h
> 
> diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig
> index cf545f428d03..10c76faa503e 100644
> --- a/drivers/soc/ti/Kconfig
> +++ b/drivers/soc/ti/Kconfig
> @@ -80,6 +80,23 @@ config TI_SCI_PM_DOMAINS
>  	  called ti_sci_pm_domains. Note this is needed early in boot before
>  	  rootfs may be available.
>  
> +config TI_K3_RINGACC
> +	tristate "K3 Ring accelerator Sub System"
> +	depends on ARCH_K3 || COMPILE_TEST
> +	depends on TI_SCI_INTA_IRQCHIP
> +	default y
> +	help
> +	  Say y here to support the K3 Ring accelerator module.
> +	  The Ring Accelerator (RINGACC or RA)  provides hardware acceleration
> +	  to enable straightforward passing of work between a producer
> +	  and a consumer. There is one RINGACC module per NAVSS on TI AM65x SoCs
> +	  If unsure, say N.
> +
> +config TI_K3_RINGACC_DEBUG
> +	tristate "K3 Ring accelerator Sub System tests and debug"
> +	depends on TI_K3_RINGACC
> +	default n
> +
>  endif # SOC_TI
>  
>  config TI_SCI_INTA_MSI_DOMAIN
> diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile
> index b3868d392d4f..cc4bc8b08bf5 100644
> --- a/drivers/soc/ti/Makefile
> +++ b/drivers/soc/ti/Makefile
> @@ -9,3 +9,4 @@ obj-$(CONFIG_AMX3_PM)			+= pm33xx.o
>  obj-$(CONFIG_WKUP_M3_IPC)		+= wkup_m3_ipc.o
>  obj-$(CONFIG_TI_SCI_PM_DOMAINS)		+= ti_sci_pm_domains.o
>  obj-$(CONFIG_TI_SCI_INTA_MSI_DOMAIN)	+= ti_sci_inta_msi.o
> +obj-$(CONFIG_TI_K3_RINGACC)		+= k3-ringacc.o
> diff --git a/drivers/soc/ti/k3-ringacc.c b/drivers/soc/ti/k3-ringacc.c
> new file mode 100644
> index 000000000000..401dfc963319
> --- /dev/null
> +++ b/drivers/soc/ti/k3-ringacc.c
> @@ -0,0 +1,1191 @@

...

> +void k3_ringacc_ring_reset_dma(struct k3_ring *ring, u32 occ)
> +{
> +	if (!ring || !(ring->flags & K3_RING_FLAG_BUSY))
> +		return;
> +
> +	if (!ring->parent->dma_ring_reset_quirk)

k3_ringacc_ring_reset(ring); is missing from here.

> +		return;
> +
> +	if (!occ)
> +		occ = dbg_readl(&ring->rt->occ);
> +
> +	if (occ) {
> +		u32 db_ring_cnt, db_ring_cnt_cur;
> +
> +		k3_nav_dbg(ring->parent->dev, "%s %u occ: %u\n", __func__,
> +			   ring->ring_id, occ);
> +		/* 2. Reset the ring */
> +		k3_ringacc_ring_reset_sci(ring);
> +
> +		/*
> +		 * 3. Setup the ring in ring/doorbell mode
> +		 * (if not already in this mode)
> +		 */
> +		if (ring->mode != K3_RINGACC_RING_MODE_RING)
> +			k3_ringacc_ring_reconfig_qmode_sci(
> +					ring, K3_RINGACC_RING_MODE_RING);
> +		/*
> +		 * 4. Ring the doorbell 2**22 – ringOcc times.
> +		 * This will wrap the internal UDMAP ring state occupancy
> +		 * counter (which is 21-bits wide) to 0.
> +		 */
> +		db_ring_cnt = (1U << 22) - occ;
> +
> +		while (db_ring_cnt != 0) {
> +			/*
> +			 * Ring the doorbell with the maximum count each
> +			 * iteration if possible to minimize the total
> +			 * of writes
> +			 */
> +			if (db_ring_cnt > K3_RINGACC_MAX_DB_RING_CNT)
> +				db_ring_cnt_cur = K3_RINGACC_MAX_DB_RING_CNT;
> +			else
> +				db_ring_cnt_cur = db_ring_cnt;
> +
> +			writel(db_ring_cnt_cur, &ring->rt->db);
> +			db_ring_cnt -= db_ring_cnt_cur;
> +		}
> +
> +		/* 5. Restore the original ring mode (if not ring mode) */
> +		if (ring->mode != K3_RINGACC_RING_MODE_RING)
> +			k3_ringacc_ring_reconfig_qmode_sci(ring, ring->mode);
> +	}
> +
> +	/* 2. Reset the ring */
> +	k3_ringacc_ring_reset(ring);
> +}
> +EXPORT_SYMBOL_GPL(k3_ringacc_ring_reset_dma);

- Péter

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