linux-kernel - Re: [PATCH v5] mmc: OCTEON: Add host driver for OCTEON MMC controller

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Date:	Fri, 12 Feb 2016 09:39:40 -0600
From:	Rob Herring <robh@...nel.org>
To:	Matt Redfearn <matt.redfearn@...tec.com>
Cc:	linux-mmc@...r.kernel.org, david.daney@...ium.com,
	ulf.hansson@...aro.org, linux-mips@...ux-mips.org,
	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Zubair.Kakakhel@...tec.com,
	Aleksey Makarov <aleksey.makarov@...iumnetworks.com>,
	Chandrakala Chavva <cchavva@...iumnetworks.com>,
	Aleksey Makarov <aleksey.makarov@...iga.com>,
	Leonid Rosenboim <lrosenboim@...iumnetworks.com>,
	Peter Swain <pswain@...ium.com>,
	Aaron Williams <aaron.williams@...ium.com>
Subject: Re: [PATCH v5] mmc: OCTEON: Add host driver for OCTEON MMC controller

On Wed, Feb 10, 2016 at 05:36:15PM +0000, Matt Redfearn wrote:
> From: Aleksey Makarov <aleksey.makarov@...iumnetworks.com>
> 
> The OCTEON MMC controller is currently found on cn61XX and cnf71XX
> devices.  Device parameters are configured from device tree data.
> 
> eMMC, MMC and SD devices are supported.
> 
> Tested-by: Aaro Koskinen <aaro.koskinen@....fi>
> Signed-off-by: Chandrakala Chavva <cchavva@...iumnetworks.com>
> Signed-off-by: David Daney <david.daney@...ium.com>
> Signed-off-by: Aleksey Makarov <aleksey.makarov@...iga.com>
> Signed-off-by: Leonid Rosenboim <lrosenboim@...iumnetworks.com>
> Signed-off-by: Peter Swain <pswain@...ium.com>
> Signed-off-by: Aaron Williams <aaron.williams@...ium.com>
> Signed-off-by: Matt Redfearn <matt.redfearn@...tec.com>
> ---
> v5:
> Incoroprate comments from review
> http://patchwork.linux-mips.org/patch/9558/
> - Use standard <bus-width> property instead of <cavium,bus-max-width>.
> - Use standard <max-frequency> property instead of <spi-max-frequency>.
> - Add octeon_mmc_of_parse_legacy function to deal with the above
>   properties, since many devices have shipped with those properties
>   embedded in firmware.
> - Allow the <vmmc-supply> binding in addition to the legacy
>   <gpios-power>.
> - Remove the secondary driver for each slot.
> - Use core gpio cd/wp handling
> 
> Tested on Rhino labs UTM8, Cavium CN7130.
> 
> For reference, the binding in the shipped devices is:
> mmc: mmc@...0000002000 {
> 	compatible = "cavium,octeon-6130-mmc";
> 	reg = <0x11800 0x00002000 0x0 0x100>,
> 		<0x11800 0x00000168 0x0 0x20>;
> 	#address-cells = <1>;
> 	#size-cells = <0>;
> 	/* EMM irq, DMA irq */
> 	interrupts = <1 19>, <0 63>;
> 
> 	/* The board only has a single MMC slot */
> 	mmc-slot@2 {
> 		compatible = "cavium,octeon-6130-mmc-slot";
> 		reg = <2>;
> 		voltage-ranges = <3300 3300>;
> 		spi-max-frequency = <26000000>;
> 		/* Power on GPIO 8, active high */
> 		/* power-gpios = <&gpio 8 0>; */
> 		power-gpios = <&gpio 8 1>;
> 
> 	/*      spi-max-frequency = <52000000>; */
> 		/* bus width can be 1, 4 or 8 */
> 		cavium,bus-max-width = <8>;
> 	};
> 	mmc-slot@0 {
> 		compatible = "cavium,octeon-6130-mmc-slot";
> 		reg = <0>;
> 		voltage-ranges = <3300 3300>;
> 		spi-max-frequency = <26000000>;
> 		/* non-removable; */
> 		bus-width = <8>;
> 		/* bus width can be 1, 4 or 8 */
> 		cavium,bus-max-width = <8>;
> 	};
> };
> 
> v3:
> https://lkml.kernel.org/g/<1425567033-31236-1-git-send-email-aleksey.makarov@...iga.com>
> 
> Changes in v4:
> - The sparse error discovered by Aaro Koskinen has been fixed
> - Other sparse warnings have been silenced
> 
> Changes in v3:
> - Rebased to v4.0-rc2
> - Use gpiod_*() functions instead of legacy gpio
> - Cosmetic changes
> 
> Changes in v2: All the fixes suggested by Mark Rutland were implemented:
> - Device tree parsing has been fixed
> - Device tree docs have been fixed
> - Comment about errata workaroud has been added
> ---
>  .../devicetree/bindings/mmc/octeon-mmc.txt         |   80 ++
>  drivers/mmc/host/Kconfig                           |   10 +
>  drivers/mmc/host/Makefile                          |    1 +
>  drivers/mmc/host/octeon_mmc.c                      | 1409 ++++++++++++++++++++
>  4 files changed, 1500 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/mmc/octeon-mmc.txt
>  create mode 100644 drivers/mmc/host/octeon_mmc.c
> 
> diff --git a/Documentation/devicetree/bindings/mmc/octeon-mmc.txt b/Documentation/devicetree/bindings/mmc/octeon-mmc.txt
> new file mode 100644
> index 000000000000..a1b20753172f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mmc/octeon-mmc.txt
> @@ -0,0 +1,80 @@
> +* OCTEON SD/MMC Host Controller
> +
> +This controller is present on some members of the Cavium OCTEON SoC
> +family, provide an interface for eMMC, MMC and SD devices.  There is a
> +single controller that may have several "slots" connected.  These
> +slots appear as children of the main controller node.
> +The DMA engine is an integral part of the controller block.
> +
> +1) MMC node
> +
> +Required properties:
> +- compatible : Should be "cavium,octeon-6130-mmc" or "cavium,octeon-7890-mmc"
> +- reg : Two entries:
> +	1) The base address of the MMC controller register bank.
> +	2) The base address of the MMC DMA engine register bank.
> +- interrupts :
> +	For "cavium,octeon-6130-mmc": two entries:
> +	1) The MMC controller interrupt line.
> +	2) The MMC DMA engine interrupt line.
> +	For "cavium,octeon-7890-mmc": nine entries:
> +	1) The next block transfer of a multiblock transfer has completed (BUF_DONE)
> +	2) Operation completed successfully (CMD_DONE).
> +	3) DMA transfer completed successfully (DMA_DONE).
> +	4) Operation encountered an error (CMD_ERR).
> +	5) DMA transfer encountered an error (DMA_ERR).
> +	6) Switch operation completed successfully (SWITCH_DONE).
> +	7) Switch operation encountered an error (SWITCH_ERR).
> +	8) Internal DMA engine request completion interrupt (DONE).
> +	9) Internal DMA FIFO underflow (FIFO).

Why do h/w designers think doing this speeds up interrupt handling...

> +- #address-cells : Must be <1>
> +- #size-cells : Must be <0>
> +
> +The node contains child nodes for each slot that the platform uses.
> +
> +Example:
> +mmc@...0000002000 {
> +	compatible = "cavium,octeon-6130-mmc";
> +	reg = <0x11800 0x00002000 0x0 0x100>,
> +		<0x11800 0x00000168 0x0 0x20>;
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +	/* EMM irq, DMA irq */
> +	interrupts = <1 19>, <0 63>;
> +
> +	[ child node definitions...]
> +};
> +
> +
> +2) Slot nodes
> +Properties in mmc.txt apply to each slot node that the platform uses.
> +
> +Required properties:
> +- reg : The slot number.
> +
> +Optional properties:
> +- cavium,cmd-clk-skew : the amount of delay (in pS) past the clock edge
> +	to sample the command pin.
> +- cavium,dat-clk-skew : the amount of delay (in pS) past the clock edge
> +	to sample the data pin.

Are you trying to maintain compatibility with legacy bindings here? If 
not, append units (-ps).

> +
> +Example:
> +	mmc@...0000002000 {
> +		compatible = "cavium,octeon-6130-mmc";
> +		reg = <0x11800 0x00002000 0x0 0x100>,
> +		      <0x11800 0x00000168 0x0 0x20>;
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		/* EMM irq, DMA irq */
> +		interrupts = <1 19>, <0 63>;
> +
> +		/* The board only has a single MMC slot */
> +		mmc-slot@0 {

Most mmc bindings don't separately describe the slot. This is probably 
a more correct h/w description, but then again I've never seen more than 
1 slot.

Otherwise, this looks fine to me.

> +			reg = <0>;
> +			max-frequency = <20000000>;
> +			bus-width = <8>;
> +			vmmc-supply = <&reg_vmmc3>;
> +			cd-gpios = <&gpio 9 0>;
> +			wp-gpios = <&gpio 10 0>;
> +		};
> +	};