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Date: Thu, 28 Apr 2016 12:11:11 +0100
From: Mark Rutland <mark.rutland@....com>
To: Sagar Dharia <sdharia@...eaurora.org>
Cc: gregkh@...uxfoundation.org, bp@...e.de, poeschel@...onage.de,
treding@...dia.com, broonie@...nel.org, gong.chen@...ux.intel.com,
andreas.noever@...il.com, alan@...ux.intel.com,
mathieu.poirier@...aro.org, daniel@...ll.ch, jkosina@...e.cz,
sharon.dvir1@...l.huji.ac.il, joe@...ches.com, davem@...emloft.net,
james.hogan@...tec.com, michael.opdenacker@...e-electrons.com,
daniel.thompson@...aro.org, robh+dt@...nel.org, pawel.moll@....com,
ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
kheitke@...ience.com, mlocke@...eaurora.org, agross@...eaurora.org,
sheetal.tigadoli@...il.com, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH V5 2/6] of/slimbus: OF helper for SLIMbus
On Wed, Apr 27, 2016 at 05:58:05PM -0600, Sagar Dharia wrote:
> OF helper routine scans the SLIMbus DeviceTree, allocates resources,
> and creates slim_devices according to the hierarchy.
>
> Signed-off-by: Sagar Dharia <sdharia@...eaurora.org>
> ---
> Documentation/devicetree/bindings/slimbus/bus.txt | 55 ++++++++++++++++++++++
> drivers/slimbus/slim-core.c | 57 +++++++++++++++++++++++
> 2 files changed, 112 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/slimbus/bus.txt
>
> diff --git a/Documentation/devicetree/bindings/slimbus/bus.txt b/Documentation/devicetree/bindings/slimbus/bus.txt
> new file mode 100644
> index 0000000..c5bb54a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/slimbus/bus.txt
> @@ -0,0 +1,55 @@
> +SLIM(Serial Low Power Interchip Media Bus) bus
> +
> +SLIMbus is a 2-wire bus, and is used to communicate with peripheral
> +components like audio-codec.
> +
> +Controller is a normal device using binding for whatever bus it is
> +on (e.g. platform bus).
> +Required property for SLIMbus controller node:
> +- compatible - name of SLIMbus controller following generic names
> + recommended practice.
> +- #address-cells - should be 4 (number of cells required to define
> + 4 fields of the enumeration address for the SLIMbus
> + slave device)
> +- #size-cells - should be 0
> +
> +No other properties are required in the SLIMbus controller bus node.
> +
> +Child nodes:
> +Every SLIMbus controller node can contain zero or more child nodes
> +representing slave devices on the bus. Every SLIMbus slave device is
> +uniquely determined by the enumeration address containing 4 fields:
> +Manufacturer ID, Product code, Device index, and Instance value for
> +the device.
> +If child node is not present and it is instantiated after device
> +discovery (slave device reporting itself present),
> +its name will be in this format: "217:60:1:0"
Per the below code, this naming detail is Linux-specific, and should go
from the binding.
> +However, the device may need additional non-standard way to power it
> +up so that it can start functioning. In that case, child node will
> +need to be present as slave of the slimbus-controller device.
> +The compatible property will be necessary so that corresponding
> +driver can probe and execute the required procedure to make it
> +functional.
> +
I imagine there may be other properties in some cases for more than
just power management, so it may be better to say:
In some cases it may be necessary to describe non-probeable
details such as non-standard ways of powering up a device. In
such cases, child nodes for those devices will be present as
slaves of the slimbus-controller, as detailed below.
> +Required property for SLIMbus child node if it is present:
> +- reg - enumeration address fields of the device
> +
> +- compatible - name of SLIMbus child node using practice typically
> + followed by discoverable buses:
> + "<manufacturer>,<product-model>", "slim"
What's the point in the "slim" fallback? That seems to imply nothing
useful, and other busses don't do that.
> +
> +SLIMbus example for Qualcomm's slimbus manager component:
> +
> + slim@...80000 {
> + compatible = "qcom,slim-msm";
> + reg = <0x28080000 0x2000>,
> + interrupts = <0 33 0>;
> + clocks = <&lcc SLIMBUS_SRC>, <&lcc AUDIO_SLIMBUS_CLK>;
> + clock-names = "iface_clk", "core_clk";
> +
> + codec@...7.0060.01.00 {
> + compatible = "qcom,wcdv1", "slim";
> + reg = <0x217 0x60 0x1 0x0>;
> + };
> + };
I'm not familiar with SLIMbus, but other than the above comments this
binding looks ok to me.
> diff --git a/drivers/slimbus/slim-core.c b/drivers/slimbus/slim-core.c
> index 6024f74..6aaa08f 100644
> --- a/drivers/slimbus/slim-core.c
> +++ b/drivers/slimbus/slim-core.c
> @@ -18,6 +18,7 @@
> #include <linux/idr.h>
> #include <linux/pm_runtime.h>
> #include <linux/slimbus.h>
> +#include <linux/of.h>
>
> static DEFINE_MUTEX(slim_lock);
> static DEFINE_IDR(ctrl_idr);
> @@ -265,6 +266,61 @@ static LIST_HEAD(board_list);
> static LIST_HEAD(slim_ctrl_list);
> static DEFINE_MUTEX(board_lock);
>
> +#if IS_ENABLED(CONFIG_OF)
> +/* OF helpers for SLIMbus */
> +static void of_register_slim_devices(struct slim_controller *ctrl)
> +{
> + struct device_node *node;
> +
> + if (!ctrl->dev.of_node)
> + return;
> +
> + for_each_child_of_node(ctrl->dev.of_node, node) {
> + int ret;
> + u32 ea[4];
> + struct slim_device *slim;
> + char *name;
> +
> + ret = of_property_read_u32_array(node, "reg", ea, 4);
> + if (ret) {
> + dev_err(&ctrl->dev, "of_slim: E-addr err:%d\n", ret);
> + continue;
> + }
> + name = kcalloc(SLIMBUS_NAME_SIZE, sizeof(char), GFP_KERNEL);
> + if (!name)
> + return;
> +
> + slim = kzalloc(sizeof(struct slim_device), GFP_KERNEL);
sizeof(*slim) would be nicer here.
Thanks,
Mark.
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