[PATCH 0/2] Add support for STM32 SPI

[PATCH 0/2] Add support for STM32 SPI

[Amelie Delaunay]

This patchset adds support for the STM32 Serial Peripheral Interface (SPI).

It applies to STM32 platforms implementing version 2 of SPI/I2S interface
like STM32H7 series.

It supports a half-duplex, full-duplex and simplex synchronous serial
communication with external devices with 4-bit to 16/32-bit per word.
It has two 8x/16x 8-bit embedded Rx and TxFIFOs with DMA capability.
It can operate in master or slave mode, but here, only master mode is
supported.

Amelie Delaunay (2):
  dt-bindings: spi: Document the STM32 SPI bindings
  spi: add driver for STM32 SPI controller

 .../devicetree/bindings/spi/spi-stm32.txt          |   60 +
 drivers/spi/Kconfig                                |   10 +
 drivers/spi/Makefile                               |    1 +
 drivers/spi/spi-stm32.c                            | 1266 ++++++++++++++++++++
 4 files changed, 1337 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spi-stm32.txt
 create mode 100644 drivers/spi/spi-stm32.c

-- 
1.9.1

[PATCH 1/2] dt-bindings: spi: Document the STM32 SPI bindings

[Amelie Delaunay]

This patch adds the documentation of device tree bindings
for the STM32 SPI controller.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
---
 .../devicetree/bindings/spi/spi-stm32.txt          | 60 ++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spi-stm32.txt

diff --git a/Documentation/devicetree/bindings/spi/spi-stm32.txt b/Documentation/devicetree/bindings/spi/spi-stm32.txt
new file mode 100644
index 0000000..3958bf6
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-stm32.txt
@@ -0,0 +1,60 @@
+STMicroelectronics STM32 SPI Controller
+
+The STM32 SPI controller is used to communicate with external devices using
+the Serial Peripheral Interface. It supports full-duplex, half-duplex and
+simplex synchronous serial communication with external devices. It supports
+from 4 to 32-bit data size. Although it can be configured as master or slave,
+only master is supported by the driver.
+
+Required properties:
+- compatible: Must be "st,stm32-spi".
+- reg: Offset and length of the device's register set.
+- interrupts: Must contain the interrupt id.
+- clocks: Must contain an entry for spiclk (which feeds the internal clock
+	  generator).
+- #address-cells:  Number of cells required to define a chip select address.
+- #size-cells: Should be zero.
+
+Optional properties:
+- resets: Must contain the phandle to the reset controller.
+- A pinctrl state named "default" may be defined to set pins in mode of
+  operation for SPI transfer.
+- dmas: DMA specifiers for tx and rx dma. DMA fifo mode must be used. See the
+  STM32 DMA bindings, Documentation/devicetree/bindings/dma/stm32-dma.txt.
+- dma-names: DMA request names should include "tx" and "rx" if present.
+- cs-gpios: list of GPIO chip selects. See the SPI bus bindings,
+  Documentation/devicetree/bindings/spi/spi-bus.txt
+
+
+Child nodes represent devices on the SPI bus
+  See ../spi/spi-bus.txt
+
+Optional properties:
+- st,spi-midi-ns: (Master Inter-Data Idleness) minimum time delay in
+		  nanoseconds inserted between two consecutive data frames.
+
+
+Example:
+	spi2: spi@40003800 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "st,stm32-spi";
+		reg = <0x40003800 0x400>;
+		interrupts = <36>;
+		clocks = <&rcc SPI2_CK>;
+		resets = <&rcc 1166>;
+		dmas = <&dmamux1 0 39 0x400 0x01>,
+		       <&dmamux1 1 40 0x400 0x01>;
+		dma-names = "rx", "tx";
+		pinctrl-0 = <&spi2_pins_b>;
+		pinctrl-names = "default";
+		status = "okay";
+		cs-gpios = <&gpioa 11 0>;
+
+		spidev@0 {
+			compatible = "spidev";
+			reg = <0>;
+			spi-max-frequency = <4000000>;
+			st,spi-midi = <4000>;
+		};
+	};
-- 
1.9.1

Applied "spi: Document the STM32 SPI bindings" to the spi tree

[Mark Brown]

The patch

   spi: Document the STM32 SPI bindings

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 82a29bf9952acd1be7e76783604686abeb4e5b1d Mon Sep 17 00:00:00 2001
From: Amelie Delaunay <amelie.delaunay@st.com>
Date: Wed, 21 Jun 2017 16:32:05 +0200
Subject: [PATCH] spi: Document the STM32 SPI bindings

This patch adds the documentation of device tree bindings
for the STM32 SPI controller.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 .../devicetree/bindings/spi/spi-stm32.txt          | 60 ++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/spi/spi-stm32.txt

diff --git a/Documentation/devicetree/bindings/spi/spi-stm32.txt b/Documentation/devicetree/bindings/spi/spi-stm32.txt
new file mode 100644
index 000000000000..3958bf6e8b37
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-stm32.txt
@@ -0,0 +1,60 @@
+STMicroelectronics STM32 SPI Controller
+
+The STM32 SPI controller is used to communicate with external devices using
+the Serial Peripheral Interface. It supports full-duplex, half-duplex and
+simplex synchronous serial communication with external devices. It supports
+from 4 to 32-bit data size. Although it can be configured as master or slave,
+only master is supported by the driver.
+
+Required properties:
+- compatible: Must be "st,stm32-spi".
+- reg: Offset and length of the device's register set.
+- interrupts: Must contain the interrupt id.
+- clocks: Must contain an entry for spiclk (which feeds the internal clock
+	  generator).
+- #address-cells:  Number of cells required to define a chip select address.
+- #size-cells: Should be zero.
+
+Optional properties:
+- resets: Must contain the phandle to the reset controller.
+- A pinctrl state named "default" may be defined to set pins in mode of
+  operation for SPI transfer.
+- dmas: DMA specifiers for tx and rx dma. DMA fifo mode must be used. See the
+  STM32 DMA bindings, Documentation/devicetree/bindings/dma/stm32-dma.txt.
+- dma-names: DMA request names should include "tx" and "rx" if present.
+- cs-gpios: list of GPIO chip selects. See the SPI bus bindings,
+  Documentation/devicetree/bindings/spi/spi-bus.txt
+
+
+Child nodes represent devices on the SPI bus
+  See ../spi/spi-bus.txt
+
+Optional properties:
+- st,spi-midi-ns: (Master Inter-Data Idleness) minimum time delay in
+		  nanoseconds inserted between two consecutive data frames.
+
+
+Example:
+	spi2: spi@40003800 {
+		#address-cells = <1>;
+		#size-cells = <0>;
+		compatible = "st,stm32-spi";
+		reg = <0x40003800 0x400>;
+		interrupts = <36>;
+		clocks = <&rcc SPI2_CK>;
+		resets = <&rcc 1166>;
+		dmas = <&dmamux1 0 39 0x400 0x01>,
+		       <&dmamux1 1 40 0x400 0x01>;
+		dma-names = "rx", "tx";
+		pinctrl-0 = <&spi2_pins_b>;
+		pinctrl-names = "default";
+		status = "okay";
+		cs-gpios = <&gpioa 11 0>;
+
+		spidev@0 {
+			compatible = "spidev";
+			reg = <0>;
+			spi-max-frequency = <4000000>;
+			st,spi-midi = <4000>;
+		};
+	};
-- 
2.11.0

Re: Applied "spi: Document the STM32 SPI bindings" to the spi tree

[Rob Herring]

On Wed, Jun 21, 2017 at 04:16:21PM +0100, Mark Brown wrote:
> The patch
> 
>    spi: Document the STM32 SPI bindings
> 
> has been applied to the spi tree at
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 
> 
> All being well this means that it will be integrated into the linux-next
> tree (usually sometime in the next 24 hours) and sent to Linus during
> the next merge window (or sooner if it is a bug fix), however if
> problems are discovered then the patch may be dropped or reverted.  
> 
> You may get further e-mails resulting from automated or manual testing
> and review of the tree, please engage with people reporting problems and
> send followup patches addressing any issues that are reported if needed.
> 
> If any updates are required or you are submitting further changes they
> should be sent as incremental updates against current git, existing
> patches will not be replaced.
> 
> Please add any relevant lists and maintainers to the CCs when replying
> to this mail.
> 
> Thanks,
> Mark
> 
> From 82a29bf9952acd1be7e76783604686abeb4e5b1d Mon Sep 17 00:00:00 2001
> From: Amelie Delaunay <amelie.delaunay@st.com>
> Date: Wed, 21 Jun 2017 16:32:05 +0200

A bit quick on the applying as there are several comments...

Rob

Re: Applied "spi: Document the STM32 SPI bindings" to the spi tree

[Mark Brown]

[-- Attachment #1: Type: text/plain, Size: 243 bytes --]

On Mon, Jun 26, 2017 at 01:22:40PM -0500, Rob Herring wrote:

> A bit quick on the applying as there are several comments...

Really trivial things which can easily be fixed incrementally without
having to repeatedly review the entire driver.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

Re: [PATCH 1/2] dt-bindings: spi: Document the STM32 SPI bindings

[Neil Armstrong]

On 06/21/2017 04:32 PM, Amelie Delaunay wrote:
> This patch adds the documentation of device tree bindings
> for the STM32 SPI controller.
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
> ---
>  .../devicetree/bindings/spi/spi-stm32.txt          | 60 ++++++++++++++++++++++
>  1 file changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/spi/spi-stm32.txt
> 
> diff --git a/Documentation/devicetree/bindings/spi/spi-stm32.txt b/Documentation/devicetree/bindings/spi/spi-stm32.txt
> new file mode 100644
> index 0000000..3958bf6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/spi-stm32.txt
> @@ -0,0 +1,60 @@
> +STMicroelectronics STM32 SPI Controller
> +
> +The STM32 SPI controller is used to communicate with external devices using
> +the Serial Peripheral Interface. It supports full-duplex, half-duplex and
> +simplex synchronous serial communication with external devices. It supports
> +from 4 to 32-bit data size. Although it can be configured as master or slave,
> +only master is supported by the driver.
> +
> +Required properties:
> +- compatible: Must be "st,stm32-spi".

Hi Amelie,

What about the gen1 SPI devices like the F4 ?

It should have been better to use SoC specific compatible, or specify the SPI HW gen like gen1 or gen2.

Neil

> +- reg: Offset and length of the device's register set.
> +- interrupts: Must contain the interrupt id.
> +- clocks: Must contain an entry for spiclk (which feeds the internal clock
> +	  generator).
> +- #address-cells:  Number of cells required to define a chip select address.
> +- #size-cells: Should be zero.
> +
> +Optional properties:
> +- resets: Must contain the phandle to the reset controller.
> +- A pinctrl state named "default" may be defined to set pins in mode of
> +  operation for SPI transfer.
> +- dmas: DMA specifiers for tx and rx dma. DMA fifo mode must be used. See the
> +  STM32 DMA bindings, Documentation/devicetree/bindings/dma/stm32-dma.txt.
> +- dma-names: DMA request names should include "tx" and "rx" if present.
> +- cs-gpios: list of GPIO chip selects. See the SPI bus bindings,
> +  Documentation/devicetree/bindings/spi/spi-bus.txt
> +
> +
> +Child nodes represent devices on the SPI bus
> +  See ../spi/spi-bus.txt
> +
> +Optional properties:
> +- st,spi-midi-ns: (Master Inter-Data Idleness) minimum time delay in
> +		  nanoseconds inserted between two consecutive data frames.
> +
> +
> +Example:
> +	spi2: spi@40003800 {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		compatible = "st,stm32-spi";
> +		reg = <0x40003800 0x400>;
> +		interrupts = <36>;
> +		clocks = <&rcc SPI2_CK>;
> +		resets = <&rcc 1166>;
> +		dmas = <&dmamux1 0 39 0x400 0x01>,
> +		       <&dmamux1 1 40 0x400 0x01>;
> +		dma-names = "rx", "tx";
> +		pinctrl-0 = <&spi2_pins_b>;
> +		pinctrl-names = "default";
> +		status = "okay";
> +		cs-gpios = <&gpioa 11 0>;
> +
> +		spidev@0 {
> +			compatible = "spidev";
> +			reg = <0>;
> +			spi-max-frequency = <4000000>;
> +			st,spi-midi = <4000>;
> +		};
> +	};
> 

Re: [PATCH 1/2] dt-bindings: spi: Document the STM32 SPI bindings

[Amelie DELAUNAY]

On 06/21/2017 05:20 PM, Neil Armstrong wrote:
> On 06/21/2017 04:32 PM, Amelie Delaunay wrote:
>> This patch adds the documentation of device tree bindings
>> for the STM32 SPI controller.
>>
>> Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
>> ---
>>   .../devicetree/bindings/spi/spi-stm32.txt          | 60 ++++++++++++++++++++++
>>   1 file changed, 60 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/spi/spi-stm32.txt
>>
>> diff --git a/Documentation/devicetree/bindings/spi/spi-stm32.txt b/Documentation/devicetree/bindings/spi/spi-stm32.txt
>> new file mode 100644
>> index 0000000..3958bf6
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/spi/spi-stm32.txt
>> @@ -0,0 +1,60 @@
>> +STMicroelectronics STM32 SPI Controller
>> +
>> +The STM32 SPI controller is used to communicate with external devices using
>> +the Serial Peripheral Interface. It supports full-duplex, half-duplex and
>> +simplex synchronous serial communication with external devices. It supports
>> +from 4 to 32-bit data size. Although it can be configured as master or slave,
>> +only master is supported by the driver.
>> +
>> +Required properties:
>> +- compatible: Must be "st,stm32-spi".
> 
> Hi Amelie,
> 
> What about the gen1 SPI devices like the F4 ?
> 
> It should have been better to use SoC specific compatible, or specify the SPI HW gen like gen1 or gen2.
> 
> Neil
> 

Hi Neil,

The gen1 SPI controller embedded on F4/F7 is different from gen2 
embedded on H7 and just to illustrate this, there are 5 main registers 
(16-bit) on gen1 versus 10 main registers on gen2 (32-bit)! Their 
operating modes are different, fifo management and so on... Moreover, I 
know that the community is working on an SPI driver for F4.

I agree with you on the fact that it would be better to use a SoC 
specific compatible: I will send a v2 with "st,stm32h7-spi". This way, 
this will be aligned with what have been done for the I2S part of this 
controller: https://patchwork.kernel.org/patch/9737799/

By the way, I also noticed that my optional property "st,spi-midi-ns" 
doesn't fit with the example "st,spi-midi". I will fix that in the v2 
and keep "st,spi-midi-ns".

Regards,
Amelie

>> +- reg: Offset and length of the device's register set.
>> +- interrupts: Must contain the interrupt id.
>> +- clocks: Must contain an entry for spiclk (which feeds the internal clock
>> +	  generator).
>> +- #address-cells:  Number of cells required to define a chip select address.
>> +- #size-cells: Should be zero.
>> +
>> +Optional properties:
>> +- resets: Must contain the phandle to the reset controller.
>> +- A pinctrl state named "default" may be defined to set pins in mode of
>> +  operation for SPI transfer.
>> +- dmas: DMA specifiers for tx and rx dma. DMA fifo mode must be used. See the
>> +  STM32 DMA bindings, Documentation/devicetree/bindings/dma/stm32-dma.txt.
>> +- dma-names: DMA request names should include "tx" and "rx" if present.
>> +- cs-gpios: list of GPIO chip selects. See the SPI bus bindings,
>> +  Documentation/devicetree/bindings/spi/spi-bus.txt
>> +
>> +
>> +Child nodes represent devices on the SPI bus
>> +  See ../spi/spi-bus.txt
>> +
>> +Optional properties:
>> +- st,spi-midi-ns: (Master Inter-Data Idleness) minimum time delay in
>> +		  nanoseconds inserted between two consecutive data frames.
>> +
>> +
>> +Example:
>> +	spi2: spi@40003800 {
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +		compatible = "st,stm32-spi";
>> +		reg = <0x40003800 0x400>;
>> +		interrupts = <36>;
>> +		clocks = <&rcc SPI2_CK>;
>> +		resets = <&rcc 1166>;
>> +		dmas = <&dmamux1 0 39 0x400 0x01>,
>> +		       <&dmamux1 1 40 0x400 0x01>;
>> +		dma-names = "rx", "tx";
>> +		pinctrl-0 = <&spi2_pins_b>;
>> +		pinctrl-names = "default";
>> +		status = "okay";
>> +		cs-gpios = <&gpioa 11 0>;
>> +
>> +		spidev@0 {
>> +			compatible = "spidev";
>> +			reg = <0>;
>> +			spi-max-frequency = <4000000>;
>> +			st,spi-midi = <4000>;
>> +		};
>> +	};
>>
> 

Re: [PATCH 1/2] dt-bindings: spi: Document the STM32 SPI bindings

[Rob Herring]

On Wed, Jun 21, 2017 at 04:32:05PM +0200, Amelie Delaunay wrote:
> This patch adds the documentation of device tree bindings
> for the STM32 SPI controller.
> 
> Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
> ---
>  .../devicetree/bindings/spi/spi-stm32.txt          | 60 ++++++++++++++++++++++
>  1 file changed, 60 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/spi/spi-stm32.txt
> 
> diff --git a/Documentation/devicetree/bindings/spi/spi-stm32.txt b/Documentation/devicetree/bindings/spi/spi-stm32.txt
> new file mode 100644
> index 0000000..3958bf6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/spi-stm32.txt
> @@ -0,0 +1,60 @@
> +STMicroelectronics STM32 SPI Controller
> +
> +The STM32 SPI controller is used to communicate with external devices using
> +the Serial Peripheral Interface. It supports full-duplex, half-duplex and
> +simplex synchronous serial communication with external devices. It supports
> +from 4 to 32-bit data size. Although it can be configured as master or slave,
> +only master is supported by the driver.
> +
> +Required properties:
> +- compatible: Must be "st,stm32-spi".
> +- reg: Offset and length of the device's register set.
> +- interrupts: Must contain the interrupt id.
> +- clocks: Must contain an entry for spiclk (which feeds the internal clock
> +	  generator).
> +- #address-cells:  Number of cells required to define a chip select address.
> +- #size-cells: Should be zero.
> +
> +Optional properties:
> +- resets: Must contain the phandle to the reset controller.
> +- A pinctrl state named "default" may be defined to set pins in mode of
> +  operation for SPI transfer.
> +- dmas: DMA specifiers for tx and rx dma. DMA fifo mode must be used. See the
> +  STM32 DMA bindings, Documentation/devicetree/bindings/dma/stm32-dma.txt.
> +- dma-names: DMA request names should include "tx" and "rx" if present.
> +- cs-gpios: list of GPIO chip selects. See the SPI bus bindings,
> +  Documentation/devicetree/bindings/spi/spi-bus.txt
> +
> +
> +Child nodes represent devices on the SPI bus
> +  See ../spi/spi-bus.txt
> +
> +Optional properties:
> +- st,spi-midi-ns: (Master Inter-Data Idleness) minimum time delay in
> +		  nanoseconds inserted between two consecutive data frames.
> +
> +
> +Example:
> +	spi2: spi@40003800 {
> +		#address-cells = <1>;
> +		#size-cells = <0>;
> +		compatible = "st,stm32-spi";
> +		reg = <0x40003800 0x400>;
> +		interrupts = <36>;
> +		clocks = <&rcc SPI2_CK>;
> +		resets = <&rcc 1166>;
> +		dmas = <&dmamux1 0 39 0x400 0x01>,
> +		       <&dmamux1 1 40 0x400 0x01>;
> +		dma-names = "rx", "tx";
> +		pinctrl-0 = <&spi2_pins_b>;
> +		pinctrl-names = "default";
> +		status = "okay";

Don't show status in examples.

> +		cs-gpios = <&gpioa 11 0>;
> +
> +		spidev@0 {
> +			compatible = "spidev";

This is not a valid compatible. Pick a real device.

Rob

Re: [PATCH 1/2] dt-bindings: spi: Document the STM32 SPI bindings

[Amelie DELAUNAY]

Hi Rob,

On 06/26/2017 08:21 PM, Rob Herring wrote:
> On Wed, Jun 21, 2017 at 04:32:05PM +0200, Amelie Delaunay wrote:
>> This patch adds the documentation of device tree bindings
>> for the STM32 SPI controller.
>>
>> Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
>> ---
>>   .../devicetree/bindings/spi/spi-stm32.txt          | 60 ++++++++++++++++++++++
>>   1 file changed, 60 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/spi/spi-stm32.txt
>>
>> diff --git a/Documentation/devicetree/bindings/spi/spi-stm32.txt b/Documentation/devicetree/bindings/spi/spi-stm32.txt
>> new file mode 100644
>> index 0000000..3958bf6
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/spi/spi-stm32.txt
>> @@ -0,0 +1,60 @@
>> +STMicroelectronics STM32 SPI Controller
>> +
>> +The STM32 SPI controller is used to communicate with external devices using
>> +the Serial Peripheral Interface. It supports full-duplex, half-duplex and
>> +simplex synchronous serial communication with external devices. It supports
>> +from 4 to 32-bit data size. Although it can be configured as master or slave,
>> +only master is supported by the driver.
>> +
>> +Required properties:
>> +- compatible: Must be "st,stm32-spi".
>> +- reg: Offset and length of the device's register set.
>> +- interrupts: Must contain the interrupt id.
>> +- clocks: Must contain an entry for spiclk (which feeds the internal clock
>> +	  generator).
>> +- #address-cells:  Number of cells required to define a chip select address.
>> +- #size-cells: Should be zero.
>> +
>> +Optional properties:
>> +- resets: Must contain the phandle to the reset controller.
>> +- A pinctrl state named "default" may be defined to set pins in mode of
>> +  operation for SPI transfer.
>> +- dmas: DMA specifiers for tx and rx dma. DMA fifo mode must be used. See the
>> +  STM32 DMA bindings, Documentation/devicetree/bindings/dma/stm32-dma.txt.
>> +- dma-names: DMA request names should include "tx" and "rx" if present.
>> +- cs-gpios: list of GPIO chip selects. See the SPI bus bindings,
>> +  Documentation/devicetree/bindings/spi/spi-bus.txt
>> +
>> +
>> +Child nodes represent devices on the SPI bus
>> +  See ../spi/spi-bus.txt
>> +
>> +Optional properties:
>> +- st,spi-midi-ns: (Master Inter-Data Idleness) minimum time delay in
>> +		  nanoseconds inserted between two consecutive data frames.
>> +
>> +
>> +Example:
>> +	spi2: spi@40003800 {
>> +		#address-cells = <1>;
>> +		#size-cells = <0>;
>> +		compatible = "st,stm32-spi";
>> +		reg = <0x40003800 0x400>;
>> +		interrupts = <36>;
>> +		clocks = <&rcc SPI2_CK>;
>> +		resets = <&rcc 1166>;
>> +		dmas = <&dmamux1 0 39 0x400 0x01>,
>> +		       <&dmamux1 1 40 0x400 0x01>;
>> +		dma-names = "rx", "tx";
>> +		pinctrl-0 = <&spi2_pins_b>;
>> +		pinctrl-names = "default";
>> +		status = "okay";
> 
> Don't show status in examples.
> 
Ok.
>> +		cs-gpios = <&gpioa 11 0>;
>> +
>> +		spidev@0 {
>> +			compatible = "spidev";
> 
> This is not a valid compatible. Pick a real device.
Ok this was just to illustrate the optional property st,spi-midi-ns.
> 
> Rob
> 

I will send a new patch to fix these issues.
Thanks,

Amelie

[PATCH 2/2] spi: add driver for STM32 SPI controller

[Amelie Delaunay]

The STM32 Serial Peripheral Interface (SPI) can be used to communicate
with external devices while using the specific synchronous protocol. It
supports a half-duplex, full-duplex and simplex synchronous, serial
communication with external devices with 4-bit to 16/32-bit per word. It
has two 8x/16x 8-bit embedded Rx and TxFIFOs with DMA capability. It can
operate in master or slave mode.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
---
 drivers/spi/Kconfig     |   10 +
 drivers/spi/Makefile    |    1 +
 drivers/spi/spi-stm32.c | 1266 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1277 insertions(+)
 create mode 100644 drivers/spi/spi-stm32.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index fd1b4fd..9b31351 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -627,6 +627,16 @@ config SPI_SIRF
 	help
 	  SPI driver for CSR SiRFprimaII SoCs
 
+config SPI_STM32
+	tristate "STMicroelectronics STM32 SPI controller"
+	depends on ARCH_STM32 || COMPILE_TEST
+	help
+	  SPI driver for STMicroelectonics STM32 SoCs.
+
+	  STM32 SPI controller supports DMA and PIO modes. When DMA
+	  is not available, the driver automatically falls back to
+	  PIO mode.
+
 config SPI_ST_SSC4
 	tristate "STMicroelectronics SPI SSC-based driver"
 	depends on ARCH_STI || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 31dccfb..a3ae2b7 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -90,6 +90,7 @@ obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
+obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o
 obj-$(CONFIG_SPI_ST_SSC4)		+= spi-st-ssc4.o
 obj-$(CONFIG_SPI_SUN4I)			+= spi-sun4i.o
 obj-$(CONFIG_SPI_SUN6I)			+= spi-sun6i.o
diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
new file mode 100644
index 0000000..0553f61
--- /dev/null
+++ b/drivers/spi/spi-stm32.c
@@ -0,0 +1,1266 @@
+/*
+ * STMicroelectronics STM32 SPI Controller driver (master mode only)
+ *
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Author(s): Amelie Delaunay <amelie.delaunay@st.com> for STMicroelectronics.
+ *
+ * License terms: GPL V2.0.
+ *
+ * spi_stm32 driver is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * spi_stm32 driver is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * spi_stm32 driver. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/debugfs.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+
+#define DRIVER_NAME "spi_stm32"
+
+/* STM32 SPI registers */
+#define STM32_SPI_CR1		0x00
+#define STM32_SPI_CR2		0x04
+#define STM32_SPI_CFG1		0x08
+#define STM32_SPI_CFG2		0x0C
+#define STM32_SPI_IER		0x10
+#define STM32_SPI_SR		0x14
+#define STM32_SPI_IFCR		0x18
+#define STM32_SPI_TXDR		0x20
+#define STM32_SPI_RXDR		0x30
+#define STM32_SPI_I2SCFGR	0x50
+
+/* STM32_SPI_CR1 bit fields */
+#define SPI_CR1_SPE		BIT(0)
+#define SPI_CR1_MASRX		BIT(8)
+#define SPI_CR1_CSTART		BIT(9)
+#define SPI_CR1_CSUSP		BIT(10)
+#define SPI_CR1_HDDIR		BIT(11)
+#define SPI_CR1_SSI		BIT(12)
+
+/* STM32_SPI_CR2 bit fields */
+#define SPI_CR2_TSIZE_SHIFT	0
+#define SPI_CR2_TSIZE		GENMASK(15, 0)
+
+/* STM32_SPI_CFG1 bit fields */
+#define SPI_CFG1_DSIZE_SHIFT	0
+#define SPI_CFG1_DSIZE		GENMASK(4, 0)
+#define SPI_CFG1_FTHLV_SHIFT	5
+#define SPI_CFG1_FTHLV		GENMASK(8, 5)
+#define SPI_CFG1_RXDMAEN	BIT(14)
+#define SPI_CFG1_TXDMAEN	BIT(15)
+#define SPI_CFG1_MBR_SHIFT	28
+#define SPI_CFG1_MBR		GENMASK(30, 28)
+#define SPI_CFG1_MBR_MIN	0
+#define SPI_CFG1_MBR_MAX	(GENMASK(30, 28) >> 28)
+
+/* STM32_SPI_CFG2 bit fields */
+#define SPI_CFG2_MIDI_SHIFT	4
+#define SPI_CFG2_MIDI		GENMASK(7, 4)
+#define SPI_CFG2_COMM_SHIFT	17
+#define SPI_CFG2_COMM		GENMASK(18, 17)
+#define SPI_CFG2_SP_SHIFT	19
+#define SPI_CFG2_SP		GENMASK(21, 19)
+#define SPI_CFG2_MASTER		BIT(22)
+#define SPI_CFG2_LSBFRST	BIT(23)
+#define SPI_CFG2_CPHA		BIT(24)
+#define SPI_CFG2_CPOL		BIT(25)
+#define SPI_CFG2_SSM		BIT(26)
+#define SPI_CFG2_AFCNTR		BIT(31)
+
+/* STM32_SPI_IER bit fields */
+#define SPI_IER_RXPIE		BIT(0)
+#define SPI_IER_TXPIE		BIT(1)
+#define SPI_IER_DXPIE		BIT(2)
+#define SPI_IER_EOTIE		BIT(3)
+#define SPI_IER_TXTFIE		BIT(4)
+#define SPI_IER_OVRIE		BIT(6)
+#define SPI_IER_MODFIE		BIT(9)
+#define SPI_IER_ALL		GENMASK(10, 0)
+
+/* STM32_SPI_SR bit fields */
+#define SPI_SR_RXP		BIT(0)
+#define SPI_SR_TXP		BIT(1)
+#define SPI_SR_EOT		BIT(3)
+#define SPI_SR_OVR		BIT(6)
+#define SPI_SR_MODF		BIT(9)
+#define SPI_SR_SUSP		BIT(11)
+#define SPI_SR_RXPLVL_SHIFT	13
+#define SPI_SR_RXPLVL		GENMASK(14, 13)
+#define SPI_SR_RXWNE		BIT(15)
+
+/* STM32_SPI_IFCR bit fields */
+#define SPI_IFCR_ALL		GENMASK(11, 3)
+
+/* STM32_SPI_I2SCFGR bit fields */
+#define SPI_I2SCFGR_I2SMOD	BIT(0)
+
+/* SPI Master Baud Rate min/max divisor */
+#define SPI_MBR_DIV_MIN		(2 << SPI_CFG1_MBR_MIN)
+#define SPI_MBR_DIV_MAX		(2 << SPI_CFG1_MBR_MAX)
+
+/* SPI Communication mode */
+#define SPI_FULL_DUPLEX		0
+#define SPI_SIMPLEX_TX		1
+#define SPI_SIMPLEX_RX		2
+#define SPI_HALF_DUPLEX		3
+
+#define SPI_1HZ_NS		1000000000
+
+/**
+ * struct stm32_spi - private data of the SPI controller
+ * @dev: driver model representation of the controller
+ * @master: controller master interface
+ * @base: virtual memory area
+ * @clk: hw kernel clock feeding the SPI clock generator
+ * @clk_rate: rate of the hw kernel clock feeding the SPI clock generator
+ * @rst: SPI controller reset line
+ * @lock: prevent I/O concurrent access
+ * @irq: SPI controller interrupt line
+ * @fifo_size: size of the embedded fifo in bytes
+ * @cur_midi: master inter-data idleness in ns
+ * @cur_speed: speed configured in Hz
+ * @cur_bpw: number of bits in a single SPI data frame
+ * @cur_fthlv: fifo threshold level (data frames in a single data packet)
+ * @cur_comm: SPI communication mode
+ * @cur_xferlen: current transfer length in bytes
+ * @cur_usedma: boolean to know if dma is used in current transfer
+ * @tx_buf: data to be written, or NULL
+ * @rx_buf: data to be read, or NULL
+ * @tx_len: number of data to be written in bytes
+ * @rx_len: number of data to be read in bytes
+ * @dma_tx: dma channel for TX transfer
+ * @dma_rx: dma channel for RX transfer
+ * @phys_addr: SPI registers physical base address
+ */
+struct stm32_spi {
+	struct device *dev;
+	struct spi_master *master;
+	void __iomem *base;
+	struct clk *clk;
+	u32 clk_rate;
+	struct reset_control *rst;
+	spinlock_t lock; /* prevent I/O concurrent access */
+	int irq;
+	unsigned int fifo_size;
+
+	unsigned int cur_midi;
+	unsigned int cur_speed;
+	unsigned int cur_bpw;
+	unsigned int cur_fthlv;
+	unsigned int cur_comm;
+	unsigned int cur_xferlen;
+	bool cur_usedma;
+
+	const void *tx_buf;
+	void *rx_buf;
+	int tx_len;
+	int rx_len;
+	struct dma_chan *dma_tx;
+	struct dma_chan *dma_rx;
+	dma_addr_t phys_addr;
+};
+
+static inline void stm32_spi_set_bits(struct stm32_spi *spi,
+				      u32 offset, u32 bits)
+{
+	writel_relaxed(readl_relaxed(spi->base + offset) | bits,
+		       spi->base + offset);
+}
+
+static inline void stm32_spi_clr_bits(struct stm32_spi *spi,
+				      u32 offset, u32 bits)
+{
+	writel_relaxed(readl_relaxed(spi->base + offset) & ~bits,
+		       spi->base + offset);
+}
+
+/**
+ * stm32_spi_get_fifo_size - Return fifo size
+ * @spi: pointer to the spi controller data structure
+ */
+static int stm32_spi_get_fifo_size(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 count = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	while (readl_relaxed(spi->base + STM32_SPI_SR) & SPI_SR_TXP)
+		writeb_relaxed(++count, spi->base + STM32_SPI_TXDR);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_dbg(spi->dev, "%d x 8-bit fifo size\n", count);
+
+	return count;
+}
+
+/**
+ * stm32_spi_get_bpw_mask - Return bits per word mask
+ * @spi: pointer to the spi controller data structure
+ */
+static int stm32_spi_get_bpw_mask(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 cfg1, max_bpw;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	/*
+	 * The most significant bit at DSIZE bit field is reserved when the
+	 * maximum data size of periperal instances is limited to 16-bit
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_DSIZE);
+
+	cfg1 = readl_relaxed(spi->base + STM32_SPI_CFG1);
+	max_bpw = (cfg1 & SPI_CFG1_DSIZE) >> SPI_CFG1_DSIZE_SHIFT;
+	max_bpw += 1;
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_dbg(spi->dev, "%d-bit maximum data frame\n", max_bpw);
+
+	return SPI_BPW_RANGE_MASK(4, max_bpw);
+}
+
+/**
+ * stm32_spi_prepare_mbr - Determine SPI_CFG1.MBR value
+ * @spi: pointer to the spi controller data structure
+ * @speed_hz: requested speed
+ *
+ * Return SPI_CFG1.MBR value in case of success or -EINVAL
+ */
+static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz)
+{
+	u32 div, mbrdiv;
+
+	div = DIV_ROUND_UP(spi->clk_rate, speed_hz);
+
+	/*
+	 * SPI framework set xfer->speed_hz to master->max_speed_hz if
+	 * xfer->speed_hz is greater than master->max_speed_hz, and it returns
+	 * an error when xfer->speed_hz is lower than master->min_speed_hz, so
+	 * no need to check it there.
+	 * However, we need to ensure the following calculations.
+	 */
+	if ((div < SPI_MBR_DIV_MIN) &&
+	    (div > SPI_MBR_DIV_MAX))
+		return -EINVAL;
+
+	/* Determine the first power of 2 greater than or equal to div */
+	mbrdiv = (div & (div - 1)) ? fls(div) : fls(div) - 1;
+
+	spi->cur_speed = spi->clk_rate / (1 << mbrdiv);
+
+	return mbrdiv - 1;
+}
+
+/**
+ * stm32_spi_prepare_fthlv - Determine FIFO threshold level
+ * @spi: pointer to the spi controller data structure
+ */
+static u32 stm32_spi_prepare_fthlv(struct stm32_spi *spi)
+{
+	u32 fthlv, half_fifo;
+
+	/* data packet should not exceed 1/2 of fifo space */
+	half_fifo = (spi->fifo_size / 2);
+
+	fthlv = (spi->cur_bpw <= 8) ? half_fifo :
+		(spi->cur_bpw <= 16) ? (half_fifo / 2) :
+		(half_fifo / 4);
+
+	/* align packet size with data registers access */
+	if (spi->cur_bpw > 8)
+		fthlv -= (fthlv % 2); /* multiple of 2 */
+	else
+		fthlv -= (fthlv % 4); /* multiple of 4 */
+
+	return fthlv;
+}
+
+/**
+ * stm32_spi_write_txfifo - Write bytes in Transmit Data Register
+ * @spi: pointer to the spi controller data structure
+ *
+ * Read from tx_buf depends on remaining bytes to avoid to read beyond
+ * tx_buf end.
+ */
+static void stm32_spi_write_txfifo(struct stm32_spi *spi)
+{
+	while ((spi->tx_len > 0) &&
+	       (readl_relaxed(spi->base + STM32_SPI_SR) & SPI_SR_TXP)) {
+		u32 offs = spi->cur_xferlen - spi->tx_len;
+
+		if (spi->tx_len >= sizeof(u32)) {
+			const u32 *tx_buf32 = (const u32 *)(spi->tx_buf + offs);
+
+			writel_relaxed(*tx_buf32, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u32);
+		} else if (spi->tx_len >= sizeof(u16)) {
+			const u16 *tx_buf16 = (const u16 *)(spi->tx_buf + offs);
+
+			writew_relaxed(*tx_buf16, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u16);
+		} else {
+			const u8 *tx_buf8 = (const u8 *)(spi->tx_buf + offs);
+
+			writeb_relaxed(*tx_buf8, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u8);
+		}
+	}
+
+	dev_dbg(spi->dev, "%s: %d bytes left\n", __func__, spi->tx_len);
+}
+
+/**
+ * stm32_spi_read_rxfifo - Read bytes in Receive Data Register
+ * @spi: pointer to the spi controller data structure
+ *
+ * Write in rx_buf depends on remaining bytes to avoid to write beyond
+ * rx_buf end.
+ */
+static void stm32_spi_read_rxfifo(struct stm32_spi *spi, bool flush)
+{
+	u32 sr = readl_relaxed(spi->base + STM32_SPI_SR);
+	u32 rxplvl = (sr & SPI_SR_RXPLVL) >> SPI_SR_RXPLVL_SHIFT;
+
+	while ((spi->rx_len > 0) &&
+	       ((sr & SPI_SR_RXP) ||
+		(flush && ((sr & SPI_SR_RXWNE) || (rxplvl > 0))))) {
+		u32 offs = spi->cur_xferlen - spi->rx_len;
+
+		if ((spi->rx_len >= sizeof(u32)) ||
+		    (flush && (sr & SPI_SR_RXWNE))) {
+			u32 *rx_buf32 = (u32 *)(spi->rx_buf + offs);
+
+			*rx_buf32 = readl_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u32);
+		} else if ((spi->rx_len >= sizeof(u16)) ||
+			   (flush && (rxplvl >= 2 || spi->cur_bpw > 8))) {
+			u16 *rx_buf16 = (u16 *)(spi->rx_buf + offs);
+
+			*rx_buf16 = readw_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u16);
+		} else {
+			u8 *rx_buf8 = (u8 *)(spi->rx_buf + offs);
+
+			*rx_buf8 = readb_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u8);
+		}
+
+		sr = readl_relaxed(spi->base + STM32_SPI_SR);
+		rxplvl = (sr & SPI_SR_RXPLVL) >> SPI_SR_RXPLVL_SHIFT;
+	}
+
+	dev_dbg(spi->dev, "%s%s: %d bytes left\n", __func__,
+		flush ? "(flush)" : "", spi->rx_len);
+}
+
+/**
+ * stm32_spi_enable - Enable SPI controller
+ * @spi: pointer to the spi controller data structure
+ *
+ * SPI data transfer is enabled but spi_ker_ck is idle.
+ * SPI_CFG1 and SPI_CFG2 are now write protected.
+ */
+static void stm32_spi_enable(struct stm32_spi *spi)
+{
+	dev_dbg(spi->dev, "enable controller\n");
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+}
+
+/**
+ * stm32_spi_disable - Disable SPI controller
+ * @spi: pointer to the spi controller data structure
+ *
+ * RX-Fifo is flushed when SPI controller is disabled. To prevent any data
+ * loss, use stm32_spi_read_rxfifo(flush) to read the remaining bytes in
+ * RX-Fifo.
+ */
+static void stm32_spi_disable(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 cr1, sr;
+
+	dev_dbg(spi->dev, "disable controller\n");
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	cr1 = readl_relaxed(spi->base + STM32_SPI_CR1);
+
+	if (!(cr1 & SPI_CR1_SPE)) {
+		spin_unlock_irqrestore(&spi->lock, flags);
+		return;
+	}
+
+	/* Wait on EOT or suspend the flow */
+	if (readl_relaxed_poll_timeout_atomic(spi->base + STM32_SPI_SR,
+					      sr, !(sr & SPI_SR_EOT),
+					      10, 100000) < 0) {
+		if (cr1 & SPI_CR1_CSTART) {
+			writel_relaxed(cr1 | SPI_CR1_CSUSP,
+				       spi->base + STM32_SPI_CR1);
+			if (readl_relaxed_poll_timeout_atomic(
+						spi->base + STM32_SPI_SR,
+						sr, !(sr & SPI_SR_SUSP),
+						10, 100000) < 0)
+				dev_warn(spi->dev,
+					 "Suspend request timeout\n");
+		}
+	}
+
+	if (!spi->cur_usedma && spi->rx_buf && (spi->rx_len > 0))
+		stm32_spi_read_rxfifo(spi, true);
+
+	if (spi->cur_usedma && spi->tx_buf)
+		dmaengine_terminate_all(spi->dma_tx);
+	if (spi->cur_usedma && spi->rx_buf)
+		dmaengine_terminate_all(spi->dma_rx);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CFG1, SPI_CFG1_TXDMAEN |
+						SPI_CFG1_RXDMAEN);
+
+	/* Disable interrupts and clear status flags */
+	writel_relaxed(0, spi->base + STM32_SPI_IER);
+	writel_relaxed(SPI_IFCR_ALL, spi->base + STM32_SPI_IFCR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+}
+
+/**
+ * stm32_spi_can_dma - Determine if the transfer is eligible for DMA use
+ *
+ * If the current transfer size is greater than fifo size, use DMA.
+ */
+static bool stm32_spi_can_dma(struct spi_master *master,
+			      struct spi_device *spi_dev,
+			      struct spi_transfer *transfer)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	dev_dbg(spi->dev, "%s: %s\n", __func__,
+		(!!(transfer->len > spi->fifo_size)) ? "true" : "false");
+
+	return !!(transfer->len > spi->fifo_size);
+}
+
+/**
+ * stm32_spi_irq - Interrupt handler for SPI controller events
+ * @irq: interrupt line
+ * @dev_id: SPI controller master interface
+ */
+static irqreturn_t stm32_spi_irq(int irq, void *dev_id)
+{
+	struct spi_master *master = dev_id;
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	u32 sr, ier, mask;
+	unsigned long flags;
+	bool end = false;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	sr = readl_relaxed(spi->base + STM32_SPI_SR);
+	ier = readl_relaxed(spi->base + STM32_SPI_IER);
+
+	mask = ier;
+	/* EOTIE is triggered on EOT, SUSP and TXC events. */
+	mask |= SPI_SR_SUSP;
+	/*
+	 * When TXTF is set, DXPIE and TXPIE are cleared. So in case of
+	 * Full-Duplex, need to poll RXP event to know if there are remaining
+	 * data, before disabling SPI.
+	 */
+	mask |= ((spi->rx_buf && !spi->cur_usedma) ? SPI_SR_RXP : 0);
+
+	if (!(sr & mask)) {
+		dev_dbg(spi->dev, "spurious IT (sr=0x%08x, ier=0x%08x)\n",
+			sr, ier);
+		spin_unlock_irqrestore(&spi->lock, flags);
+		return IRQ_NONE;
+	}
+
+	if (sr & SPI_SR_SUSP) {
+		dev_warn(spi->dev, "Communication suspended\n");
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+	}
+
+	if (sr & SPI_SR_MODF) {
+		dev_warn(spi->dev, "Mode fault: transfer aborted\n");
+		end = true;
+	}
+
+	if (sr & SPI_SR_OVR) {
+		dev_warn(spi->dev, "Overrun: received value discarded\n");
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+	}
+
+	if (sr & SPI_SR_EOT) {
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, true);
+		end = true;
+	}
+
+	if (sr & SPI_SR_TXP)
+		if (!spi->cur_usedma && (spi->tx_buf && (spi->tx_len > 0)))
+			stm32_spi_write_txfifo(spi);
+
+	if (sr & SPI_SR_RXP)
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+
+	writel_relaxed(mask, spi->base + STM32_SPI_IFCR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	if (end) {
+		spi_finalize_current_transfer(master);
+		stm32_spi_disable(spi);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * stm32_spi_setup - setup device chip select
+ */
+static int stm32_spi_setup(struct spi_device *spi_dev)
+{
+	int ret = 0;
+
+	if (!gpio_is_valid(spi_dev->cs_gpio)) {
+		dev_err(&spi_dev->dev, "%d is not a valid gpio\n",
+			spi_dev->cs_gpio);
+		return -EINVAL;
+	}
+
+	dev_dbg(&spi_dev->dev, "%s: set gpio%d output %s\n", __func__,
+		spi_dev->cs_gpio,
+		(spi_dev->mode & SPI_CS_HIGH) ? "low" : "high");
+
+	ret = gpio_direction_output(spi_dev->cs_gpio,
+				    !(spi_dev->mode & SPI_CS_HIGH));
+
+	return ret;
+}
+
+/**
+ * stm32_spi_prepare_msg - set up the controller to transfer a single message
+ */
+static int stm32_spi_prepare_msg(struct spi_master *master,
+				 struct spi_message *msg)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	struct spi_device *spi_dev = msg->spi;
+	struct device_node *np = spi_dev->dev.of_node;
+	unsigned long flags;
+	u32 cfg2_clrb = 0, cfg2_setb = 0;
+
+	/* SPI slave device may need time between data frames */
+	spi->cur_midi = 0;
+	if (np && !of_property_read_u32(np, "st,spi-midi", &spi->cur_midi))
+		dev_dbg(spi->dev, "%dns inter-data idleness\n", spi->cur_midi);
+
+	if (spi_dev->mode & SPI_CPOL)
+		cfg2_setb |= SPI_CFG2_CPOL;
+	else
+		cfg2_clrb |= SPI_CFG2_CPOL;
+
+	if (spi_dev->mode & SPI_CPHA)
+		cfg2_setb |= SPI_CFG2_CPHA;
+	else
+		cfg2_clrb |= SPI_CFG2_CPHA;
+
+	if (spi_dev->mode & SPI_LSB_FIRST)
+		cfg2_setb |= SPI_CFG2_LSBFRST;
+	else
+		cfg2_clrb |= SPI_CFG2_LSBFRST;
+
+	dev_dbg(spi->dev, "cpol=%d cpha=%d lsb_first=%d cs_high=%d\n",
+		spi_dev->mode & SPI_CPOL,
+		spi_dev->mode & SPI_CPHA,
+		spi_dev->mode & SPI_LSB_FIRST,
+		spi_dev->mode & SPI_CS_HIGH);
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	if (cfg2_clrb || cfg2_setb)
+		writel_relaxed(
+			(readl_relaxed(spi->base + STM32_SPI_CFG2) &
+				~cfg2_clrb) | cfg2_setb,
+			       spi->base + STM32_SPI_CFG2);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 0;
+}
+
+/**
+ * stm32_spi_dma_cb - dma callback
+ *
+ * DMA callback is called when the transfer is complete or when an error
+ * occurs. If the transfer is complete, EOT flag is raised.
+ */
+static void stm32_spi_dma_cb(void *data)
+{
+	struct stm32_spi *spi = data;
+	unsigned long flags;
+	u32 sr;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	sr = readl_relaxed(spi->base + STM32_SPI_SR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	if (!(sr & SPI_SR_EOT)) {
+		dev_warn(spi->dev, "DMA callback (sr=0x%08x)\n", sr);
+
+		spi_finalize_current_transfer(spi->master);
+		stm32_spi_disable(spi);
+	}
+}
+
+/**
+ * stm32_spi_dma_config - configure dma slave channel depending on current
+ *			  transfer bits_per_word.
+ */
+static void stm32_spi_dma_config(struct stm32_spi *spi,
+				 struct dma_slave_config *dma_conf,
+				 enum dma_transfer_direction dir)
+{
+	enum dma_slave_buswidth buswidth;
+	u32 maxburst;
+
+	buswidth = (spi->cur_bpw <= 8) ? DMA_SLAVE_BUSWIDTH_1_BYTE :
+		   (spi->cur_bpw <= 16) ? DMA_SLAVE_BUSWIDTH_2_BYTES :
+		   DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+	/* Valid for DMA Half or Full Fifo threshold */
+	maxburst = (spi->cur_fthlv == 2) ? 1 : spi->cur_fthlv;
+
+	memset(dma_conf, 0, sizeof(struct dma_slave_config));
+	dma_conf->direction = dir;
+	if (dma_conf->direction == DMA_DEV_TO_MEM) { /* RX */
+		dma_conf->src_addr = spi->phys_addr + STM32_SPI_RXDR;
+		dma_conf->src_addr_width = buswidth;
+		dma_conf->src_maxburst = maxburst;
+
+		dev_dbg(spi->dev, "Rx DMA config buswidth=%d, maxburst=%d\n",
+			buswidth, maxburst);
+	} else if (dma_conf->direction == DMA_MEM_TO_DEV) { /* TX */
+		dma_conf->dst_addr = spi->phys_addr + STM32_SPI_TXDR;
+		dma_conf->dst_addr_width = buswidth;
+		dma_conf->dst_maxburst = maxburst;
+
+		dev_dbg(spi->dev, "Tx DMA config buswidth=%d, maxburst=%d\n",
+			buswidth, maxburst);
+	}
+}
+
+/**
+ * stm32_spi_transfer_one_irq - transfer a single spi_transfer using
+ *				interrupts
+ *
+ * It must returns 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one_irq(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 ier = 0;
+
+	/* Enable the interrupts relative to the current communication mode */
+	if (spi->tx_buf && spi->rx_buf)	/* Full Duplex */
+		ier |= SPI_IER_DXPIE;
+	else if (spi->tx_buf)		/* Half-Duplex TX dir or Simplex TX */
+		ier |= SPI_IER_TXPIE;
+	else if (spi->rx_buf)		/* Half-Duplex RX dir or Simplex RX */
+		ier |= SPI_IER_RXPIE;
+
+	/* Enable the interrupts relative to the end of transfer */
+	ier |= SPI_IER_EOTIE | SPI_IER_TXTFIE |	SPI_IER_OVRIE |	SPI_IER_MODFIE;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	stm32_spi_enable(spi);
+
+	/* Be sure to have data in fifo before starting data transfer */
+	if (spi->tx_buf)
+		stm32_spi_write_txfifo(spi);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_CSTART);
+
+	writel_relaxed(ier, spi->base + STM32_SPI_IER);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 1;
+}
+
+/**
+ * stm32_spi_transfer_one_dma - transfer a single spi_transfer using DMA
+ *
+ * It must returns 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
+				      struct spi_transfer *xfer)
+{
+	struct dma_slave_config tx_dma_conf, rx_dma_conf;
+	struct dma_async_tx_descriptor *tx_dma_desc, *rx_dma_desc;
+	unsigned long flags;
+	u32 ier = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	rx_dma_desc = NULL;
+	if (spi->rx_buf) {
+		stm32_spi_dma_config(spi, &rx_dma_conf, DMA_DEV_TO_MEM);
+		dmaengine_slave_config(spi->dma_rx, &rx_dma_conf);
+
+		/* Enable Rx DMA request */
+		stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_RXDMAEN);
+
+		rx_dma_desc = dmaengine_prep_slave_sg(
+					spi->dma_rx, xfer->rx_sg.sgl,
+					xfer->rx_sg.nents,
+					rx_dma_conf.direction,
+					DMA_PREP_INTERRUPT);
+
+		rx_dma_desc->callback = stm32_spi_dma_cb;
+		rx_dma_desc->callback_param = spi;
+	}
+
+	tx_dma_desc = NULL;
+	if (spi->tx_buf) {
+		stm32_spi_dma_config(spi, &tx_dma_conf, DMA_MEM_TO_DEV);
+		dmaengine_slave_config(spi->dma_tx, &tx_dma_conf);
+
+		tx_dma_desc = dmaengine_prep_slave_sg(
+					spi->dma_tx, xfer->tx_sg.sgl,
+					xfer->tx_sg.nents,
+					tx_dma_conf.direction,
+					DMA_PREP_INTERRUPT);
+
+		if (spi->cur_comm == SPI_SIMPLEX_TX) {
+			tx_dma_desc->callback = stm32_spi_dma_cb;
+			tx_dma_desc->callback_param = spi;
+		}
+	}
+
+	if ((spi->tx_buf && !tx_dma_desc) ||
+	    (spi->rx_buf && !rx_dma_desc))
+		goto dma_desc_error;
+
+	if (rx_dma_desc) {
+		if (dma_submit_error(dmaengine_submit(rx_dma_desc))) {
+			dev_err(spi->dev, "Rx DMA submit failed\n");
+			goto dma_desc_error;
+		}
+		/* Enable Rx DMA channel */
+		dma_async_issue_pending(spi->dma_rx);
+	}
+
+	if (tx_dma_desc) {
+		if (dma_submit_error(dmaengine_submit(tx_dma_desc))) {
+			dev_err(spi->dev, "Tx DMA submit failed\n");
+			goto dma_submit_error;
+		}
+		/* Enable Tx DMA channel */
+		dma_async_issue_pending(spi->dma_tx);
+
+		/* Enable Tx DMA request */
+		stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_TXDMAEN);
+	}
+
+	/* Enable the interrupts relative to the end of transfer */
+	ier |= SPI_IER_EOTIE | SPI_IER_TXTFIE |	SPI_IER_OVRIE |	SPI_IER_MODFIE;
+	writel_relaxed(ier, spi->base + STM32_SPI_IER);
+
+	stm32_spi_enable(spi);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_CSTART);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 1;
+
+dma_submit_error:
+	if (spi->rx_buf)
+		dmaengine_terminate_all(spi->dma_rx);
+
+dma_desc_error:
+	stm32_spi_clr_bits(spi, STM32_SPI_CFG1, SPI_CFG1_RXDMAEN);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_info(spi->dev, "DMA issue: fall back to irq transfer\n");
+
+	return stm32_spi_transfer_one_irq(spi);
+}
+
+/**
+ * stm32_spi_transfer_one_setup - common setup to transfer a single
+ *				  spi_transfer either using DMA or
+ *				  interrupts.
+ */
+static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
+					struct spi_device *spi_dev,
+					struct spi_transfer *transfer)
+{
+	unsigned long flags;
+	u32 cfg1_clrb = 0, cfg1_setb = 0, cfg2_clrb = 0, cfg2_setb = 0;
+	u32 mode, nb_words;
+	int ret = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	if (spi->cur_bpw != transfer->bits_per_word) {
+		u32 bpw, fthlv;
+
+		spi->cur_bpw = transfer->bits_per_word;
+		bpw = spi->cur_bpw - 1;
+
+		cfg1_clrb |= SPI_CFG1_DSIZE;
+		cfg1_setb |= (bpw << SPI_CFG1_DSIZE_SHIFT) & SPI_CFG1_DSIZE;
+
+		spi->cur_fthlv = stm32_spi_prepare_fthlv(spi);
+		fthlv = spi->cur_fthlv - 1;
+
+		cfg1_clrb |= SPI_CFG1_FTHLV;
+		cfg1_setb |= (fthlv << SPI_CFG1_FTHLV_SHIFT) & SPI_CFG1_FTHLV;
+	}
+
+	if (spi->cur_speed != transfer->speed_hz) {
+		u32 mbr;
+
+		/* Update spi->cur_speed with real clock speed */
+		mbr = stm32_spi_prepare_mbr(spi, transfer->speed_hz);
+		if (mbr < 0) {
+			ret = mbr;
+			goto out;
+		}
+
+		transfer->speed_hz = spi->cur_speed;
+
+		cfg1_clrb |= SPI_CFG1_MBR;
+		cfg1_setb |= (mbr << SPI_CFG1_MBR_SHIFT) & SPI_CFG1_MBR;
+	}
+
+	if (cfg1_clrb || cfg1_setb)
+		writel_relaxed((readl_relaxed(spi->base + STM32_SPI_CFG1) &
+				~cfg1_clrb) | cfg1_setb,
+			       spi->base + STM32_SPI_CFG1);
+
+	mode = SPI_FULL_DUPLEX;
+	if (spi_dev->mode & SPI_3WIRE) { /* MISO/MOSI signals shared */
+		/*
+		 * SPI_3WIRE and xfer->tx_buf != NULL and xfer->rx_buf != NULL
+		 * is forbidden und unvalidated by SPI subsystem so depending
+		 * on the valid buffer, we can determine the direction of the
+		 * transfer.
+		 */
+		mode = SPI_HALF_DUPLEX;
+		if (!transfer->tx_buf)
+			stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_HDDIR);
+		else if (!transfer->rx_buf)
+			stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_HDDIR);
+	} else {
+		if (!transfer->tx_buf)
+			mode = SPI_SIMPLEX_RX;
+		else if (!transfer->rx_buf)
+			mode = SPI_SIMPLEX_TX;
+	}
+	if (spi->cur_comm != mode) {
+		spi->cur_comm = mode;
+
+		cfg2_clrb |= SPI_CFG2_COMM;
+		cfg2_setb |= (mode << SPI_CFG2_COMM_SHIFT) & SPI_CFG2_COMM;
+	}
+
+	cfg2_clrb |= SPI_CFG2_MIDI;
+	if ((transfer->len > 1) && (spi->cur_midi > 0)) {
+		u32 sck_period_ns = DIV_ROUND_UP(SPI_1HZ_NS, spi->cur_speed);
+		u32 midi = min((u32)DIV_ROUND_UP(spi->cur_midi, sck_period_ns),
+			       (u32)SPI_CFG2_MIDI >> SPI_CFG2_MIDI_SHIFT);
+
+		dev_dbg(spi->dev, "period=%dns, midi=%d(=%dns)\n",
+			sck_period_ns, midi, midi * sck_period_ns);
+
+		cfg2_setb |= (midi << SPI_CFG2_MIDI_SHIFT) & SPI_CFG2_MIDI;
+	}
+
+	if (cfg2_clrb || cfg2_setb)
+		writel_relaxed((readl_relaxed(spi->base + STM32_SPI_CFG2) &
+				~cfg2_clrb) | cfg2_setb,
+			       spi->base + STM32_SPI_CFG2);
+
+	nb_words = DIV_ROUND_UP(transfer->len * 8,
+				(spi->cur_bpw <= 8) ? 8 :
+				(spi->cur_bpw <= 16) ? 16 : 32);
+	nb_words <<= SPI_CR2_TSIZE_SHIFT;
+
+	if (nb_words <= SPI_CR2_TSIZE) {
+		writel_relaxed(nb_words, spi->base + STM32_SPI_CR2);
+	} else {
+		ret = -EMSGSIZE;
+		goto out;
+	}
+
+	spi->cur_xferlen = transfer->len;
+
+	dev_dbg(spi->dev, "transfer communication mode set to %d\n",
+		spi->cur_comm);
+	dev_dbg(spi->dev,
+		"data frame of %d-bit, data packet of %d data frames\n",
+		spi->cur_bpw, spi->cur_fthlv);
+	dev_dbg(spi->dev, "speed set to %dHz\n", spi->cur_speed);
+	dev_dbg(spi->dev, "transfer of %d bytes (%d data frames)\n",
+		spi->cur_xferlen, nb_words);
+	dev_dbg(spi->dev, "dma %s\n",
+		(spi->cur_usedma) ? "enabled" : "disabled");
+
+out:
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return ret;
+}
+
+/**
+ * stm32_spi_transfer_one - transfer a single spi_transfer
+ *
+ * It must return 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one(struct spi_master *master,
+				  struct spi_device *spi_dev,
+				  struct spi_transfer *transfer)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	spi->tx_buf = transfer->tx_buf;
+	spi->rx_buf = transfer->rx_buf;
+	spi->tx_len = spi->tx_buf ? transfer->len : 0;
+	spi->rx_len = spi->rx_buf ? transfer->len : 0;
+
+	spi->cur_usedma = stm32_spi_can_dma(master, spi_dev, transfer);
+
+	ret = stm32_spi_transfer_one_setup(spi, spi_dev, transfer);
+	if (ret) {
+		dev_err(spi->dev, "SPI transfer setup failed\n");
+		return ret;
+	}
+
+	if (spi->cur_usedma)
+		return stm32_spi_transfer_one_dma(spi, transfer);
+	else
+		return stm32_spi_transfer_one_irq(spi);
+}
+
+/**
+ * stm32_spi_unprepare_msg - relax the hardware
+ *
+ * Normally, if TSIZE has been configured, we should relax the hardware at the
+ * reception of the EOT interrupt. But in case of error, EOT will not be
+ * raised. So the subsystem unprepare_message call allows us to properly
+ * complete the transfer from an hardware point of view.
+ */
+static int stm32_spi_unprepare_msg(struct spi_master *master,
+				   struct spi_message *msg)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	stm32_spi_disable(spi);
+
+	return 0;
+}
+
+/**
+ * stm32_spi_config - Configure SPI controller as SPI master
+ */
+static int stm32_spi_config(struct stm32_spi *spi)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	/* Ensure I2SMOD bit is kept cleared */
+	stm32_spi_clr_bits(spi, STM32_SPI_I2SCFGR, SPI_I2SCFGR_I2SMOD);
+
+	/*
+	 * - SS input value high
+	 * - transmitter half duplex direction
+	 * - automatic communication suspend when RX-Fifo is full
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SSI |
+					       SPI_CR1_HDDIR |
+					       SPI_CR1_MASRX);
+
+	/*
+	 * - Set the master mode (default Motorola mode)
+	 * - Consider 1 master/n slaves configuration and
+	 *   SS input value is determined by the SSI bit
+	 * - keep control of all associated GPIOs
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CFG2, SPI_CFG2_MASTER |
+						SPI_CFG2_SSM |
+						SPI_CFG2_AFCNTR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 0;
+}
+
+static const struct of_device_id stm32_spi_of_match[] = {
+	{ .compatible = "st,stm32-spi", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stm32_spi_of_match);
+
+static int stm32_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct stm32_spi *spi;
+	struct resource *res;
+	int i, ret;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct stm32_spi));
+	if (!master) {
+		dev_err(&pdev->dev, "spi master allocation failed\n");
+		return -ENOMEM;
+	}
+	platform_set_drvdata(pdev, master);
+
+	spi = spi_master_get_devdata(master);
+	spi->dev = &pdev->dev;
+	spi->master = master;
+	spin_lock_init(&spi->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	spi->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(spi->base)) {
+		ret = PTR_ERR(spi->base);
+		goto err_master_put;
+	}
+	spi->phys_addr = (dma_addr_t)res->start;
+
+	spi->irq = platform_get_irq(pdev, 0);
+	if (spi->irq <= 0) {
+		dev_err(&pdev->dev, "no irq: %d\n", spi->irq);
+		ret = -ENOENT;
+		goto err_master_put;
+	}
+	ret = devm_request_threaded_irq(&pdev->dev, spi->irq, NULL,
+					stm32_spi_irq, IRQF_ONESHOT,
+					pdev->name, master);
+	if (ret) {
+		dev_err(&pdev->dev, "irq%d request failed: %d\n", spi->irq,
+			ret);
+		goto err_master_put;
+	}
+
+	spi->clk = devm_clk_get(&pdev->dev, 0);
+	if (IS_ERR(spi->clk)) {
+		ret = PTR_ERR(spi->clk);
+		dev_err(&pdev->dev, "clk get failed: %d\n", ret);
+		goto err_master_put;
+	}
+
+	ret = clk_prepare_enable(spi->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "clk enable failed: %d\n", ret);
+		goto err_master_put;
+	}
+	spi->clk_rate = clk_get_rate(spi->clk);
+	if (!spi->clk_rate) {
+		dev_err(&pdev->dev, "clk rate = 0\n");
+		ret = -EINVAL;
+		goto err_master_put;
+	}
+
+	spi->rst = devm_reset_control_get(&pdev->dev, NULL);
+	if (!IS_ERR(spi->rst)) {
+		reset_control_assert(spi->rst);
+		udelay(2);
+		reset_control_deassert(spi->rst);
+	}
+
+	spi->fifo_size = stm32_spi_get_fifo_size(spi);
+
+	ret = stm32_spi_config(spi);
+	if (ret) {
+		dev_err(&pdev->dev, "controller configuration failed: %d\n",
+			ret);
+		goto err_clk_disable;
+	}
+
+	master->dev.of_node = pdev->dev.of_node;
+	master->auto_runtime_pm = true;
+	master->bus_num = pdev->id;
+	master->mode_bits = SPI_MODE_3 | SPI_CS_HIGH | SPI_LSB_FIRST |
+			    SPI_3WIRE | SPI_LOOP;
+	master->bits_per_word_mask = stm32_spi_get_bpw_mask(spi);
+	master->max_speed_hz = spi->clk_rate / SPI_MBR_DIV_MIN;
+	master->min_speed_hz = spi->clk_rate / SPI_MBR_DIV_MAX;
+	master->setup = stm32_spi_setup;
+	master->prepare_message = stm32_spi_prepare_msg;
+	master->transfer_one = stm32_spi_transfer_one;
+	master->unprepare_message = stm32_spi_unprepare_msg;
+
+	spi->dma_tx = dma_request_slave_channel(spi->dev, "tx");
+	if (!spi->dma_tx)
+		dev_warn(&pdev->dev, "failed to request tx dma channel\n");
+	else
+		master->dma_tx = spi->dma_tx;
+
+	spi->dma_rx = dma_request_slave_channel(spi->dev, "rx");
+	if (!spi->dma_rx)
+		dev_warn(&pdev->dev, "failed to request rx dma channel\n");
+	else
+		master->dma_rx = spi->dma_rx;
+
+	if (spi->dma_tx || spi->dma_rx)
+		master->can_dma = stm32_spi_can_dma;
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (ret) {
+		dev_err(&pdev->dev, "spi master registration failed: %d\n",
+			ret);
+		goto err_dma_release;
+	}
+
+	if (!master->cs_gpios) {
+		dev_err(&pdev->dev, "no CS gpios available\n");
+		ret = -EINVAL;
+		goto err_dma_release;
+	}
+
+	for (i = 0; i < master->num_chipselect; i++) {
+		if (!gpio_is_valid(master->cs_gpios[i])) {
+			dev_err(&pdev->dev, "%i is not a valid gpio\n",
+				master->cs_gpios[i]);
+			ret = -EINVAL;
+			goto err_dma_release;
+		}
+
+		ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
+					DRIVER_NAME);
+		if (ret) {
+			dev_err(&pdev->dev, "can't get CS gpio %i\n",
+				master->cs_gpios[i]);
+			goto err_dma_release;
+		}
+	}
+
+	dev_info(&pdev->dev, "driver initialized\n");
+
+	return 0;
+
+err_dma_release:
+	if (spi->dma_tx)
+		dma_release_channel(spi->dma_tx);
+	if (spi->dma_rx)
+		dma_release_channel(spi->dma_rx);
+err_clk_disable:
+	clk_disable_unprepare(spi->clk);
+err_master_put:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int stm32_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	stm32_spi_disable(spi);
+
+	if (master->dma_tx)
+		dma_release_channel(master->dma_tx);
+	if (master->dma_rx)
+		dma_release_channel(master->dma_rx);
+
+	clk_disable_unprepare(spi->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int stm32_spi_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = spi_master_suspend(master);
+	if (ret)
+		return ret;
+
+	clk_disable_unprepare(spi->clk);
+
+	return ret;
+}
+
+static int stm32_spi_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = clk_prepare_enable(spi->clk);
+	if (ret)
+		return ret;
+	ret = spi_master_resume(master);
+	if (ret)
+		clk_disable_unprepare(spi->clk);
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(stm32_spi_pm_ops,
+			 stm32_spi_suspend, stm32_spi_resume);
+
+static struct platform_driver stm32_spi_driver = {
+	.probe = stm32_spi_probe,
+	.remove = stm32_spi_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.pm = &stm32_spi_pm_ops,
+		.of_match_table = stm32_spi_of_match,
+	},
+};
+
+module_platform_driver(stm32_spi_driver);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_DESCRIPTION("STMicroelectronics STM32 SPI Controller driver");
+MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

Re: [PATCH 2/2] spi: add driver for STM32 SPI controller

[Mark Brown]

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On Wed, Jun 21, 2017 at 04:32:06PM +0200, Amelie Delaunay wrote:

A few minor stylistic things but overall this looks really nice, please
send followup patches fixing these style things.

> +	/* Determine the first power of 2 greater than or equal to div */
> +	mbrdiv = (div & (div - 1)) ? fls(div) : fls(div) - 1;

Please write normal conditional statements, it makes things much easier
to read.

> +static bool stm32_spi_can_dma(struct spi_master *master,
> +			      struct spi_device *spi_dev,
> +			      struct spi_transfer *transfer)
> +{
> +	struct stm32_spi *spi = spi_master_get_devdata(master);
> +
> +	dev_dbg(spi->dev, "%s: %s\n", __func__,
> +		(!!(transfer->len > spi->fifo_size)) ? "true" : "false");
> +
> +	return !!(transfer->len > spi->fifo_size);

This !! is redundant, you're converting a boolean value into a boolean
value.

> +	buswidth = (spi->cur_bpw <= 8) ? DMA_SLAVE_BUSWIDTH_1_BYTE :
> +		   (spi->cur_bpw <= 16) ? DMA_SLAVE_BUSWIDTH_2_BYTES :
> +		   DMA_SLAVE_BUSWIDTH_4_BYTES;
> +
> +	/* Valid for DMA Half or Full Fifo threshold */
> +	maxburst = (spi->cur_fthlv == 2) ? 1 : spi->cur_fthlv;

Again, please use normal conditional statements - people have to read
things.

> +static int stm32_spi_suspend(struct device *dev)
> +{
> +	struct spi_master *master = dev_get_drvdata(dev);
> +	struct stm32_spi *spi = spi_master_get_devdata(master);
> +	int ret;
> +
> +	ret = spi_master_suspend(master);
> +	if (ret)
> +		return ret;
> +
> +	clk_disable_unprepare(spi->clk);

It'd be good to also have the clock disabled by runtime PM, that will
save a little more power.  There's support for enabling and disabling
the device in the core so it should just be adding callbacks.  Not
essential though.

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Re: [PATCH 2/2] spi: add driver for STM32 SPI controller

[Amelie DELAUNAY]

Hi Mark,

Thanks for your review.

On 06/21/2017 05:13 PM, Mark Brown wrote:
> On Wed, Jun 21, 2017 at 04:32:06PM +0200, Amelie Delaunay wrote:
> 
> A few minor stylistic things but overall this looks really nice, please
> send followup patches fixing these style things.
> 
>> +	/* Determine the first power of 2 greater than or equal to div */
>> +	mbrdiv = (div & (div - 1)) ? fls(div) : fls(div) - 1;
> 
> Please write normal conditional statements, it makes things much easier
> to read.
> OK, I'll fix it in v2.

>> +static bool stm32_spi_can_dma(struct spi_master *master,
>> +			      struct spi_device *spi_dev,
>> +			      struct spi_transfer *transfer)
>> +{
>> +	struct stm32_spi *spi = spi_master_get_devdata(master);
>> +
>> +	dev_dbg(spi->dev, "%s: %s\n", __func__,
>> +		(!!(transfer->len > spi->fifo_size)) ? "true" : "false");
>> +
>> +	return !!(transfer->len > spi->fifo_size);
> 
> This !! is redundant, you're converting a boolean value into a boolean
> value.
> 
You're right.

>> +	buswidth = (spi->cur_bpw <= 8) ? DMA_SLAVE_BUSWIDTH_1_BYTE :
>> +		   (spi->cur_bpw <= 16) ? DMA_SLAVE_BUSWIDTH_2_BYTES :
>> +		   DMA_SLAVE_BUSWIDTH_4_BYTES;
>> +
>> +	/* Valid for DMA Half or Full Fifo threshold */
>> +	maxburst = (spi->cur_fthlv == 2) ? 1 : spi->cur_fthlv;
> 
> Again, please use normal conditional statements - people have to read
> things.
> 
OK.
>> +static int stm32_spi_suspend(struct device *dev)
>> +{
>> +	struct spi_master *master = dev_get_drvdata(dev);
>> +	struct stm32_spi *spi = spi_master_get_devdata(master);
>> +	int ret;
>> +
>> +	ret = spi_master_suspend(master);
>> +	if (ret)
>> +		return ret;
>> +
>> +	clk_disable_unprepare(spi->clk);
> 
> It'd be good to also have the clock disabled by runtime PM, that will
> save a little more power.  There's support for enabling and disabling
> the device in the core so it should just be adding callbacks.  Not
> essential though.
> 
OK I'll have a look.

Regards,
Amelie

Applied "spi: add driver for STM32 SPI controller" to the spi tree

[Mark Brown]

The patch

   spi: add driver for STM32 SPI controller

has been applied to the spi tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From dcbe0d84dfa5a3e72b8e6ce622cd5ac78abbcab8 Mon Sep 17 00:00:00 2001
From: Amelie Delaunay <amelie.delaunay@st.com>
Date: Wed, 21 Jun 2017 16:32:06 +0200
Subject: [PATCH] spi: add driver for STM32 SPI controller

The STM32 Serial Peripheral Interface (SPI) can be used to communicate
with external devices while using the specific synchronous protocol. It
supports a half-duplex, full-duplex and simplex synchronous, serial
communication with external devices with 4-bit to 16/32-bit per word. It
has two 8x/16x 8-bit embedded Rx and TxFIFOs with DMA capability. It can
operate in master or slave mode.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
---
 drivers/spi/Kconfig     |   10 +
 drivers/spi/Makefile    |    1 +
 drivers/spi/spi-stm32.c | 1266 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 1277 insertions(+)
 create mode 100644 drivers/spi/spi-stm32.c

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 1761c9004fc1..36f3f90f07a2 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -619,6 +619,16 @@ config SPI_SIRF
 	help
 	  SPI driver for CSR SiRFprimaII SoCs
 
+config SPI_STM32
+	tristate "STMicroelectronics STM32 SPI controller"
+	depends on ARCH_STM32 || COMPILE_TEST
+	help
+	  SPI driver for STMicroelectonics STM32 SoCs.
+
+	  STM32 SPI controller supports DMA and PIO modes. When DMA
+	  is not available, the driver automatically falls back to
+	  PIO mode.
+
 config SPI_ST_SSC4
 	tristate "STMicroelectronics SPI SSC-based driver"
 	depends on ARCH_STI || COMPILE_TEST
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index b375a7a89216..6b0749cc28bf 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -89,6 +89,7 @@ obj-$(CONFIG_SPI_SH_HSPI)		+= spi-sh-hspi.o
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
+obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o
 obj-$(CONFIG_SPI_ST_SSC4)		+= spi-st-ssc4.o
 obj-$(CONFIG_SPI_SUN4I)			+= spi-sun4i.o
 obj-$(CONFIG_SPI_SUN6I)			+= spi-sun6i.o
diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
new file mode 100644
index 000000000000..0553f61ab3b7
--- /dev/null
+++ b/drivers/spi/spi-stm32.c
@@ -0,0 +1,1266 @@
+/*
+ * STMicroelectronics STM32 SPI Controller driver (master mode only)
+ *
+ * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
+ * Author(s): Amelie Delaunay <amelie.delaunay@st.com> for STMicroelectronics.
+ *
+ * License terms: GPL V2.0.
+ *
+ * spi_stm32 driver is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * spi_stm32 driver is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * spi_stm32 driver. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/debugfs.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dmaengine.h>
+#include <linux/gpio.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+
+#define DRIVER_NAME "spi_stm32"
+
+/* STM32 SPI registers */
+#define STM32_SPI_CR1		0x00
+#define STM32_SPI_CR2		0x04
+#define STM32_SPI_CFG1		0x08
+#define STM32_SPI_CFG2		0x0C
+#define STM32_SPI_IER		0x10
+#define STM32_SPI_SR		0x14
+#define STM32_SPI_IFCR		0x18
+#define STM32_SPI_TXDR		0x20
+#define STM32_SPI_RXDR		0x30
+#define STM32_SPI_I2SCFGR	0x50
+
+/* STM32_SPI_CR1 bit fields */
+#define SPI_CR1_SPE		BIT(0)
+#define SPI_CR1_MASRX		BIT(8)
+#define SPI_CR1_CSTART		BIT(9)
+#define SPI_CR1_CSUSP		BIT(10)
+#define SPI_CR1_HDDIR		BIT(11)
+#define SPI_CR1_SSI		BIT(12)
+
+/* STM32_SPI_CR2 bit fields */
+#define SPI_CR2_TSIZE_SHIFT	0
+#define SPI_CR2_TSIZE		GENMASK(15, 0)
+
+/* STM32_SPI_CFG1 bit fields */
+#define SPI_CFG1_DSIZE_SHIFT	0
+#define SPI_CFG1_DSIZE		GENMASK(4, 0)
+#define SPI_CFG1_FTHLV_SHIFT	5
+#define SPI_CFG1_FTHLV		GENMASK(8, 5)
+#define SPI_CFG1_RXDMAEN	BIT(14)
+#define SPI_CFG1_TXDMAEN	BIT(15)
+#define SPI_CFG1_MBR_SHIFT	28
+#define SPI_CFG1_MBR		GENMASK(30, 28)
+#define SPI_CFG1_MBR_MIN	0
+#define SPI_CFG1_MBR_MAX	(GENMASK(30, 28) >> 28)
+
+/* STM32_SPI_CFG2 bit fields */
+#define SPI_CFG2_MIDI_SHIFT	4
+#define SPI_CFG2_MIDI		GENMASK(7, 4)
+#define SPI_CFG2_COMM_SHIFT	17
+#define SPI_CFG2_COMM		GENMASK(18, 17)
+#define SPI_CFG2_SP_SHIFT	19
+#define SPI_CFG2_SP		GENMASK(21, 19)
+#define SPI_CFG2_MASTER		BIT(22)
+#define SPI_CFG2_LSBFRST	BIT(23)
+#define SPI_CFG2_CPHA		BIT(24)
+#define SPI_CFG2_CPOL		BIT(25)
+#define SPI_CFG2_SSM		BIT(26)
+#define SPI_CFG2_AFCNTR		BIT(31)
+
+/* STM32_SPI_IER bit fields */
+#define SPI_IER_RXPIE		BIT(0)
+#define SPI_IER_TXPIE		BIT(1)
+#define SPI_IER_DXPIE		BIT(2)
+#define SPI_IER_EOTIE		BIT(3)
+#define SPI_IER_TXTFIE		BIT(4)
+#define SPI_IER_OVRIE		BIT(6)
+#define SPI_IER_MODFIE		BIT(9)
+#define SPI_IER_ALL		GENMASK(10, 0)
+
+/* STM32_SPI_SR bit fields */
+#define SPI_SR_RXP		BIT(0)
+#define SPI_SR_TXP		BIT(1)
+#define SPI_SR_EOT		BIT(3)
+#define SPI_SR_OVR		BIT(6)
+#define SPI_SR_MODF		BIT(9)
+#define SPI_SR_SUSP		BIT(11)
+#define SPI_SR_RXPLVL_SHIFT	13
+#define SPI_SR_RXPLVL		GENMASK(14, 13)
+#define SPI_SR_RXWNE		BIT(15)
+
+/* STM32_SPI_IFCR bit fields */
+#define SPI_IFCR_ALL		GENMASK(11, 3)
+
+/* STM32_SPI_I2SCFGR bit fields */
+#define SPI_I2SCFGR_I2SMOD	BIT(0)
+
+/* SPI Master Baud Rate min/max divisor */
+#define SPI_MBR_DIV_MIN		(2 << SPI_CFG1_MBR_MIN)
+#define SPI_MBR_DIV_MAX		(2 << SPI_CFG1_MBR_MAX)
+
+/* SPI Communication mode */
+#define SPI_FULL_DUPLEX		0
+#define SPI_SIMPLEX_TX		1
+#define SPI_SIMPLEX_RX		2
+#define SPI_HALF_DUPLEX		3
+
+#define SPI_1HZ_NS		1000000000
+
+/**
+ * struct stm32_spi - private data of the SPI controller
+ * @dev: driver model representation of the controller
+ * @master: controller master interface
+ * @base: virtual memory area
+ * @clk: hw kernel clock feeding the SPI clock generator
+ * @clk_rate: rate of the hw kernel clock feeding the SPI clock generator
+ * @rst: SPI controller reset line
+ * @lock: prevent I/O concurrent access
+ * @irq: SPI controller interrupt line
+ * @fifo_size: size of the embedded fifo in bytes
+ * @cur_midi: master inter-data idleness in ns
+ * @cur_speed: speed configured in Hz
+ * @cur_bpw: number of bits in a single SPI data frame
+ * @cur_fthlv: fifo threshold level (data frames in a single data packet)
+ * @cur_comm: SPI communication mode
+ * @cur_xferlen: current transfer length in bytes
+ * @cur_usedma: boolean to know if dma is used in current transfer
+ * @tx_buf: data to be written, or NULL
+ * @rx_buf: data to be read, or NULL
+ * @tx_len: number of data to be written in bytes
+ * @rx_len: number of data to be read in bytes
+ * @dma_tx: dma channel for TX transfer
+ * @dma_rx: dma channel for RX transfer
+ * @phys_addr: SPI registers physical base address
+ */
+struct stm32_spi {
+	struct device *dev;
+	struct spi_master *master;
+	void __iomem *base;
+	struct clk *clk;
+	u32 clk_rate;
+	struct reset_control *rst;
+	spinlock_t lock; /* prevent I/O concurrent access */
+	int irq;
+	unsigned int fifo_size;
+
+	unsigned int cur_midi;
+	unsigned int cur_speed;
+	unsigned int cur_bpw;
+	unsigned int cur_fthlv;
+	unsigned int cur_comm;
+	unsigned int cur_xferlen;
+	bool cur_usedma;
+
+	const void *tx_buf;
+	void *rx_buf;
+	int tx_len;
+	int rx_len;
+	struct dma_chan *dma_tx;
+	struct dma_chan *dma_rx;
+	dma_addr_t phys_addr;
+};
+
+static inline void stm32_spi_set_bits(struct stm32_spi *spi,
+				      u32 offset, u32 bits)
+{
+	writel_relaxed(readl_relaxed(spi->base + offset) | bits,
+		       spi->base + offset);
+}
+
+static inline void stm32_spi_clr_bits(struct stm32_spi *spi,
+				      u32 offset, u32 bits)
+{
+	writel_relaxed(readl_relaxed(spi->base + offset) & ~bits,
+		       spi->base + offset);
+}
+
+/**
+ * stm32_spi_get_fifo_size - Return fifo size
+ * @spi: pointer to the spi controller data structure
+ */
+static int stm32_spi_get_fifo_size(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 count = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	while (readl_relaxed(spi->base + STM32_SPI_SR) & SPI_SR_TXP)
+		writeb_relaxed(++count, spi->base + STM32_SPI_TXDR);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_dbg(spi->dev, "%d x 8-bit fifo size\n", count);
+
+	return count;
+}
+
+/**
+ * stm32_spi_get_bpw_mask - Return bits per word mask
+ * @spi: pointer to the spi controller data structure
+ */
+static int stm32_spi_get_bpw_mask(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 cfg1, max_bpw;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	/*
+	 * The most significant bit at DSIZE bit field is reserved when the
+	 * maximum data size of periperal instances is limited to 16-bit
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_DSIZE);
+
+	cfg1 = readl_relaxed(spi->base + STM32_SPI_CFG1);
+	max_bpw = (cfg1 & SPI_CFG1_DSIZE) >> SPI_CFG1_DSIZE_SHIFT;
+	max_bpw += 1;
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_dbg(spi->dev, "%d-bit maximum data frame\n", max_bpw);
+
+	return SPI_BPW_RANGE_MASK(4, max_bpw);
+}
+
+/**
+ * stm32_spi_prepare_mbr - Determine SPI_CFG1.MBR value
+ * @spi: pointer to the spi controller data structure
+ * @speed_hz: requested speed
+ *
+ * Return SPI_CFG1.MBR value in case of success or -EINVAL
+ */
+static int stm32_spi_prepare_mbr(struct stm32_spi *spi, u32 speed_hz)
+{
+	u32 div, mbrdiv;
+
+	div = DIV_ROUND_UP(spi->clk_rate, speed_hz);
+
+	/*
+	 * SPI framework set xfer->speed_hz to master->max_speed_hz if
+	 * xfer->speed_hz is greater than master->max_speed_hz, and it returns
+	 * an error when xfer->speed_hz is lower than master->min_speed_hz, so
+	 * no need to check it there.
+	 * However, we need to ensure the following calculations.
+	 */
+	if ((div < SPI_MBR_DIV_MIN) &&
+	    (div > SPI_MBR_DIV_MAX))
+		return -EINVAL;
+
+	/* Determine the first power of 2 greater than or equal to div */
+	mbrdiv = (div & (div - 1)) ? fls(div) : fls(div) - 1;
+
+	spi->cur_speed = spi->clk_rate / (1 << mbrdiv);
+
+	return mbrdiv - 1;
+}
+
+/**
+ * stm32_spi_prepare_fthlv - Determine FIFO threshold level
+ * @spi: pointer to the spi controller data structure
+ */
+static u32 stm32_spi_prepare_fthlv(struct stm32_spi *spi)
+{
+	u32 fthlv, half_fifo;
+
+	/* data packet should not exceed 1/2 of fifo space */
+	half_fifo = (spi->fifo_size / 2);
+
+	fthlv = (spi->cur_bpw <= 8) ? half_fifo :
+		(spi->cur_bpw <= 16) ? (half_fifo / 2) :
+		(half_fifo / 4);
+
+	/* align packet size with data registers access */
+	if (spi->cur_bpw > 8)
+		fthlv -= (fthlv % 2); /* multiple of 2 */
+	else
+		fthlv -= (fthlv % 4); /* multiple of 4 */
+
+	return fthlv;
+}
+
+/**
+ * stm32_spi_write_txfifo - Write bytes in Transmit Data Register
+ * @spi: pointer to the spi controller data structure
+ *
+ * Read from tx_buf depends on remaining bytes to avoid to read beyond
+ * tx_buf end.
+ */
+static void stm32_spi_write_txfifo(struct stm32_spi *spi)
+{
+	while ((spi->tx_len > 0) &&
+	       (readl_relaxed(spi->base + STM32_SPI_SR) & SPI_SR_TXP)) {
+		u32 offs = spi->cur_xferlen - spi->tx_len;
+
+		if (spi->tx_len >= sizeof(u32)) {
+			const u32 *tx_buf32 = (const u32 *)(spi->tx_buf + offs);
+
+			writel_relaxed(*tx_buf32, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u32);
+		} else if (spi->tx_len >= sizeof(u16)) {
+			const u16 *tx_buf16 = (const u16 *)(spi->tx_buf + offs);
+
+			writew_relaxed(*tx_buf16, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u16);
+		} else {
+			const u8 *tx_buf8 = (const u8 *)(spi->tx_buf + offs);
+
+			writeb_relaxed(*tx_buf8, spi->base + STM32_SPI_TXDR);
+			spi->tx_len -= sizeof(u8);
+		}
+	}
+
+	dev_dbg(spi->dev, "%s: %d bytes left\n", __func__, spi->tx_len);
+}
+
+/**
+ * stm32_spi_read_rxfifo - Read bytes in Receive Data Register
+ * @spi: pointer to the spi controller data structure
+ *
+ * Write in rx_buf depends on remaining bytes to avoid to write beyond
+ * rx_buf end.
+ */
+static void stm32_spi_read_rxfifo(struct stm32_spi *spi, bool flush)
+{
+	u32 sr = readl_relaxed(spi->base + STM32_SPI_SR);
+	u32 rxplvl = (sr & SPI_SR_RXPLVL) >> SPI_SR_RXPLVL_SHIFT;
+
+	while ((spi->rx_len > 0) &&
+	       ((sr & SPI_SR_RXP) ||
+		(flush && ((sr & SPI_SR_RXWNE) || (rxplvl > 0))))) {
+		u32 offs = spi->cur_xferlen - spi->rx_len;
+
+		if ((spi->rx_len >= sizeof(u32)) ||
+		    (flush && (sr & SPI_SR_RXWNE))) {
+			u32 *rx_buf32 = (u32 *)(spi->rx_buf + offs);
+
+			*rx_buf32 = readl_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u32);
+		} else if ((spi->rx_len >= sizeof(u16)) ||
+			   (flush && (rxplvl >= 2 || spi->cur_bpw > 8))) {
+			u16 *rx_buf16 = (u16 *)(spi->rx_buf + offs);
+
+			*rx_buf16 = readw_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u16);
+		} else {
+			u8 *rx_buf8 = (u8 *)(spi->rx_buf + offs);
+
+			*rx_buf8 = readb_relaxed(spi->base + STM32_SPI_RXDR);
+			spi->rx_len -= sizeof(u8);
+		}
+
+		sr = readl_relaxed(spi->base + STM32_SPI_SR);
+		rxplvl = (sr & SPI_SR_RXPLVL) >> SPI_SR_RXPLVL_SHIFT;
+	}
+
+	dev_dbg(spi->dev, "%s%s: %d bytes left\n", __func__,
+		flush ? "(flush)" : "", spi->rx_len);
+}
+
+/**
+ * stm32_spi_enable - Enable SPI controller
+ * @spi: pointer to the spi controller data structure
+ *
+ * SPI data transfer is enabled but spi_ker_ck is idle.
+ * SPI_CFG1 and SPI_CFG2 are now write protected.
+ */
+static void stm32_spi_enable(struct stm32_spi *spi)
+{
+	dev_dbg(spi->dev, "enable controller\n");
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+}
+
+/**
+ * stm32_spi_disable - Disable SPI controller
+ * @spi: pointer to the spi controller data structure
+ *
+ * RX-Fifo is flushed when SPI controller is disabled. To prevent any data
+ * loss, use stm32_spi_read_rxfifo(flush) to read the remaining bytes in
+ * RX-Fifo.
+ */
+static void stm32_spi_disable(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 cr1, sr;
+
+	dev_dbg(spi->dev, "disable controller\n");
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	cr1 = readl_relaxed(spi->base + STM32_SPI_CR1);
+
+	if (!(cr1 & SPI_CR1_SPE)) {
+		spin_unlock_irqrestore(&spi->lock, flags);
+		return;
+	}
+
+	/* Wait on EOT or suspend the flow */
+	if (readl_relaxed_poll_timeout_atomic(spi->base + STM32_SPI_SR,
+					      sr, !(sr & SPI_SR_EOT),
+					      10, 100000) < 0) {
+		if (cr1 & SPI_CR1_CSTART) {
+			writel_relaxed(cr1 | SPI_CR1_CSUSP,
+				       spi->base + STM32_SPI_CR1);
+			if (readl_relaxed_poll_timeout_atomic(
+						spi->base + STM32_SPI_SR,
+						sr, !(sr & SPI_SR_SUSP),
+						10, 100000) < 0)
+				dev_warn(spi->dev,
+					 "Suspend request timeout\n");
+		}
+	}
+
+	if (!spi->cur_usedma && spi->rx_buf && (spi->rx_len > 0))
+		stm32_spi_read_rxfifo(spi, true);
+
+	if (spi->cur_usedma && spi->tx_buf)
+		dmaengine_terminate_all(spi->dma_tx);
+	if (spi->cur_usedma && spi->rx_buf)
+		dmaengine_terminate_all(spi->dma_rx);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_SPE);
+
+	stm32_spi_clr_bits(spi, STM32_SPI_CFG1, SPI_CFG1_TXDMAEN |
+						SPI_CFG1_RXDMAEN);
+
+	/* Disable interrupts and clear status flags */
+	writel_relaxed(0, spi->base + STM32_SPI_IER);
+	writel_relaxed(SPI_IFCR_ALL, spi->base + STM32_SPI_IFCR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+}
+
+/**
+ * stm32_spi_can_dma - Determine if the transfer is eligible for DMA use
+ *
+ * If the current transfer size is greater than fifo size, use DMA.
+ */
+static bool stm32_spi_can_dma(struct spi_master *master,
+			      struct spi_device *spi_dev,
+			      struct spi_transfer *transfer)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	dev_dbg(spi->dev, "%s: %s\n", __func__,
+		(!!(transfer->len > spi->fifo_size)) ? "true" : "false");
+
+	return !!(transfer->len > spi->fifo_size);
+}
+
+/**
+ * stm32_spi_irq - Interrupt handler for SPI controller events
+ * @irq: interrupt line
+ * @dev_id: SPI controller master interface
+ */
+static irqreturn_t stm32_spi_irq(int irq, void *dev_id)
+{
+	struct spi_master *master = dev_id;
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	u32 sr, ier, mask;
+	unsigned long flags;
+	bool end = false;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	sr = readl_relaxed(spi->base + STM32_SPI_SR);
+	ier = readl_relaxed(spi->base + STM32_SPI_IER);
+
+	mask = ier;
+	/* EOTIE is triggered on EOT, SUSP and TXC events. */
+	mask |= SPI_SR_SUSP;
+	/*
+	 * When TXTF is set, DXPIE and TXPIE are cleared. So in case of
+	 * Full-Duplex, need to poll RXP event to know if there are remaining
+	 * data, before disabling SPI.
+	 */
+	mask |= ((spi->rx_buf && !spi->cur_usedma) ? SPI_SR_RXP : 0);
+
+	if (!(sr & mask)) {
+		dev_dbg(spi->dev, "spurious IT (sr=0x%08x, ier=0x%08x)\n",
+			sr, ier);
+		spin_unlock_irqrestore(&spi->lock, flags);
+		return IRQ_NONE;
+	}
+
+	if (sr & SPI_SR_SUSP) {
+		dev_warn(spi->dev, "Communication suspended\n");
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+	}
+
+	if (sr & SPI_SR_MODF) {
+		dev_warn(spi->dev, "Mode fault: transfer aborted\n");
+		end = true;
+	}
+
+	if (sr & SPI_SR_OVR) {
+		dev_warn(spi->dev, "Overrun: received value discarded\n");
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+	}
+
+	if (sr & SPI_SR_EOT) {
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, true);
+		end = true;
+	}
+
+	if (sr & SPI_SR_TXP)
+		if (!spi->cur_usedma && (spi->tx_buf && (spi->tx_len > 0)))
+			stm32_spi_write_txfifo(spi);
+
+	if (sr & SPI_SR_RXP)
+		if (!spi->cur_usedma && (spi->rx_buf && (spi->rx_len > 0)))
+			stm32_spi_read_rxfifo(spi, false);
+
+	writel_relaxed(mask, spi->base + STM32_SPI_IFCR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	if (end) {
+		spi_finalize_current_transfer(master);
+		stm32_spi_disable(spi);
+	}
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * stm32_spi_setup - setup device chip select
+ */
+static int stm32_spi_setup(struct spi_device *spi_dev)
+{
+	int ret = 0;
+
+	if (!gpio_is_valid(spi_dev->cs_gpio)) {
+		dev_err(&spi_dev->dev, "%d is not a valid gpio\n",
+			spi_dev->cs_gpio);
+		return -EINVAL;
+	}
+
+	dev_dbg(&spi_dev->dev, "%s: set gpio%d output %s\n", __func__,
+		spi_dev->cs_gpio,
+		(spi_dev->mode & SPI_CS_HIGH) ? "low" : "high");
+
+	ret = gpio_direction_output(spi_dev->cs_gpio,
+				    !(spi_dev->mode & SPI_CS_HIGH));
+
+	return ret;
+}
+
+/**
+ * stm32_spi_prepare_msg - set up the controller to transfer a single message
+ */
+static int stm32_spi_prepare_msg(struct spi_master *master,
+				 struct spi_message *msg)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	struct spi_device *spi_dev = msg->spi;
+	struct device_node *np = spi_dev->dev.of_node;
+	unsigned long flags;
+	u32 cfg2_clrb = 0, cfg2_setb = 0;
+
+	/* SPI slave device may need time between data frames */
+	spi->cur_midi = 0;
+	if (np && !of_property_read_u32(np, "st,spi-midi", &spi->cur_midi))
+		dev_dbg(spi->dev, "%dns inter-data idleness\n", spi->cur_midi);
+
+	if (spi_dev->mode & SPI_CPOL)
+		cfg2_setb |= SPI_CFG2_CPOL;
+	else
+		cfg2_clrb |= SPI_CFG2_CPOL;
+
+	if (spi_dev->mode & SPI_CPHA)
+		cfg2_setb |= SPI_CFG2_CPHA;
+	else
+		cfg2_clrb |= SPI_CFG2_CPHA;
+
+	if (spi_dev->mode & SPI_LSB_FIRST)
+		cfg2_setb |= SPI_CFG2_LSBFRST;
+	else
+		cfg2_clrb |= SPI_CFG2_LSBFRST;
+
+	dev_dbg(spi->dev, "cpol=%d cpha=%d lsb_first=%d cs_high=%d\n",
+		spi_dev->mode & SPI_CPOL,
+		spi_dev->mode & SPI_CPHA,
+		spi_dev->mode & SPI_LSB_FIRST,
+		spi_dev->mode & SPI_CS_HIGH);
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	if (cfg2_clrb || cfg2_setb)
+		writel_relaxed(
+			(readl_relaxed(spi->base + STM32_SPI_CFG2) &
+				~cfg2_clrb) | cfg2_setb,
+			       spi->base + STM32_SPI_CFG2);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 0;
+}
+
+/**
+ * stm32_spi_dma_cb - dma callback
+ *
+ * DMA callback is called when the transfer is complete or when an error
+ * occurs. If the transfer is complete, EOT flag is raised.
+ */
+static void stm32_spi_dma_cb(void *data)
+{
+	struct stm32_spi *spi = data;
+	unsigned long flags;
+	u32 sr;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	sr = readl_relaxed(spi->base + STM32_SPI_SR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	if (!(sr & SPI_SR_EOT)) {
+		dev_warn(spi->dev, "DMA callback (sr=0x%08x)\n", sr);
+
+		spi_finalize_current_transfer(spi->master);
+		stm32_spi_disable(spi);
+	}
+}
+
+/**
+ * stm32_spi_dma_config - configure dma slave channel depending on current
+ *			  transfer bits_per_word.
+ */
+static void stm32_spi_dma_config(struct stm32_spi *spi,
+				 struct dma_slave_config *dma_conf,
+				 enum dma_transfer_direction dir)
+{
+	enum dma_slave_buswidth buswidth;
+	u32 maxburst;
+
+	buswidth = (spi->cur_bpw <= 8) ? DMA_SLAVE_BUSWIDTH_1_BYTE :
+		   (spi->cur_bpw <= 16) ? DMA_SLAVE_BUSWIDTH_2_BYTES :
+		   DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+	/* Valid for DMA Half or Full Fifo threshold */
+	maxburst = (spi->cur_fthlv == 2) ? 1 : spi->cur_fthlv;
+
+	memset(dma_conf, 0, sizeof(struct dma_slave_config));
+	dma_conf->direction = dir;
+	if (dma_conf->direction == DMA_DEV_TO_MEM) { /* RX */
+		dma_conf->src_addr = spi->phys_addr + STM32_SPI_RXDR;
+		dma_conf->src_addr_width = buswidth;
+		dma_conf->src_maxburst = maxburst;
+
+		dev_dbg(spi->dev, "Rx DMA config buswidth=%d, maxburst=%d\n",
+			buswidth, maxburst);
+	} else if (dma_conf->direction == DMA_MEM_TO_DEV) { /* TX */
+		dma_conf->dst_addr = spi->phys_addr + STM32_SPI_TXDR;
+		dma_conf->dst_addr_width = buswidth;
+		dma_conf->dst_maxburst = maxburst;
+
+		dev_dbg(spi->dev, "Tx DMA config buswidth=%d, maxburst=%d\n",
+			buswidth, maxburst);
+	}
+}
+
+/**
+ * stm32_spi_transfer_one_irq - transfer a single spi_transfer using
+ *				interrupts
+ *
+ * It must returns 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one_irq(struct stm32_spi *spi)
+{
+	unsigned long flags;
+	u32 ier = 0;
+
+	/* Enable the interrupts relative to the current communication mode */
+	if (spi->tx_buf && spi->rx_buf)	/* Full Duplex */
+		ier |= SPI_IER_DXPIE;
+	else if (spi->tx_buf)		/* Half-Duplex TX dir or Simplex TX */
+		ier |= SPI_IER_TXPIE;
+	else if (spi->rx_buf)		/* Half-Duplex RX dir or Simplex RX */
+		ier |= SPI_IER_RXPIE;
+
+	/* Enable the interrupts relative to the end of transfer */
+	ier |= SPI_IER_EOTIE | SPI_IER_TXTFIE |	SPI_IER_OVRIE |	SPI_IER_MODFIE;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	stm32_spi_enable(spi);
+
+	/* Be sure to have data in fifo before starting data transfer */
+	if (spi->tx_buf)
+		stm32_spi_write_txfifo(spi);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_CSTART);
+
+	writel_relaxed(ier, spi->base + STM32_SPI_IER);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 1;
+}
+
+/**
+ * stm32_spi_transfer_one_dma - transfer a single spi_transfer using DMA
+ *
+ * It must returns 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one_dma(struct stm32_spi *spi,
+				      struct spi_transfer *xfer)
+{
+	struct dma_slave_config tx_dma_conf, rx_dma_conf;
+	struct dma_async_tx_descriptor *tx_dma_desc, *rx_dma_desc;
+	unsigned long flags;
+	u32 ier = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	rx_dma_desc = NULL;
+	if (spi->rx_buf) {
+		stm32_spi_dma_config(spi, &rx_dma_conf, DMA_DEV_TO_MEM);
+		dmaengine_slave_config(spi->dma_rx, &rx_dma_conf);
+
+		/* Enable Rx DMA request */
+		stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_RXDMAEN);
+
+		rx_dma_desc = dmaengine_prep_slave_sg(
+					spi->dma_rx, xfer->rx_sg.sgl,
+					xfer->rx_sg.nents,
+					rx_dma_conf.direction,
+					DMA_PREP_INTERRUPT);
+
+		rx_dma_desc->callback = stm32_spi_dma_cb;
+		rx_dma_desc->callback_param = spi;
+	}
+
+	tx_dma_desc = NULL;
+	if (spi->tx_buf) {
+		stm32_spi_dma_config(spi, &tx_dma_conf, DMA_MEM_TO_DEV);
+		dmaengine_slave_config(spi->dma_tx, &tx_dma_conf);
+
+		tx_dma_desc = dmaengine_prep_slave_sg(
+					spi->dma_tx, xfer->tx_sg.sgl,
+					xfer->tx_sg.nents,
+					tx_dma_conf.direction,
+					DMA_PREP_INTERRUPT);
+
+		if (spi->cur_comm == SPI_SIMPLEX_TX) {
+			tx_dma_desc->callback = stm32_spi_dma_cb;
+			tx_dma_desc->callback_param = spi;
+		}
+	}
+
+	if ((spi->tx_buf && !tx_dma_desc) ||
+	    (spi->rx_buf && !rx_dma_desc))
+		goto dma_desc_error;
+
+	if (rx_dma_desc) {
+		if (dma_submit_error(dmaengine_submit(rx_dma_desc))) {
+			dev_err(spi->dev, "Rx DMA submit failed\n");
+			goto dma_desc_error;
+		}
+		/* Enable Rx DMA channel */
+		dma_async_issue_pending(spi->dma_rx);
+	}
+
+	if (tx_dma_desc) {
+		if (dma_submit_error(dmaengine_submit(tx_dma_desc))) {
+			dev_err(spi->dev, "Tx DMA submit failed\n");
+			goto dma_submit_error;
+		}
+		/* Enable Tx DMA channel */
+		dma_async_issue_pending(spi->dma_tx);
+
+		/* Enable Tx DMA request */
+		stm32_spi_set_bits(spi, STM32_SPI_CFG1, SPI_CFG1_TXDMAEN);
+	}
+
+	/* Enable the interrupts relative to the end of transfer */
+	ier |= SPI_IER_EOTIE | SPI_IER_TXTFIE |	SPI_IER_OVRIE |	SPI_IER_MODFIE;
+	writel_relaxed(ier, spi->base + STM32_SPI_IER);
+
+	stm32_spi_enable(spi);
+
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_CSTART);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 1;
+
+dma_submit_error:
+	if (spi->rx_buf)
+		dmaengine_terminate_all(spi->dma_rx);
+
+dma_desc_error:
+	stm32_spi_clr_bits(spi, STM32_SPI_CFG1, SPI_CFG1_RXDMAEN);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	dev_info(spi->dev, "DMA issue: fall back to irq transfer\n");
+
+	return stm32_spi_transfer_one_irq(spi);
+}
+
+/**
+ * stm32_spi_transfer_one_setup - common setup to transfer a single
+ *				  spi_transfer either using DMA or
+ *				  interrupts.
+ */
+static int stm32_spi_transfer_one_setup(struct stm32_spi *spi,
+					struct spi_device *spi_dev,
+					struct spi_transfer *transfer)
+{
+	unsigned long flags;
+	u32 cfg1_clrb = 0, cfg1_setb = 0, cfg2_clrb = 0, cfg2_setb = 0;
+	u32 mode, nb_words;
+	int ret = 0;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	if (spi->cur_bpw != transfer->bits_per_word) {
+		u32 bpw, fthlv;
+
+		spi->cur_bpw = transfer->bits_per_word;
+		bpw = spi->cur_bpw - 1;
+
+		cfg1_clrb |= SPI_CFG1_DSIZE;
+		cfg1_setb |= (bpw << SPI_CFG1_DSIZE_SHIFT) & SPI_CFG1_DSIZE;
+
+		spi->cur_fthlv = stm32_spi_prepare_fthlv(spi);
+		fthlv = spi->cur_fthlv - 1;
+
+		cfg1_clrb |= SPI_CFG1_FTHLV;
+		cfg1_setb |= (fthlv << SPI_CFG1_FTHLV_SHIFT) & SPI_CFG1_FTHLV;
+	}
+
+	if (spi->cur_speed != transfer->speed_hz) {
+		u32 mbr;
+
+		/* Update spi->cur_speed with real clock speed */
+		mbr = stm32_spi_prepare_mbr(spi, transfer->speed_hz);
+		if (mbr < 0) {
+			ret = mbr;
+			goto out;
+		}
+
+		transfer->speed_hz = spi->cur_speed;
+
+		cfg1_clrb |= SPI_CFG1_MBR;
+		cfg1_setb |= (mbr << SPI_CFG1_MBR_SHIFT) & SPI_CFG1_MBR;
+	}
+
+	if (cfg1_clrb || cfg1_setb)
+		writel_relaxed((readl_relaxed(spi->base + STM32_SPI_CFG1) &
+				~cfg1_clrb) | cfg1_setb,
+			       spi->base + STM32_SPI_CFG1);
+
+	mode = SPI_FULL_DUPLEX;
+	if (spi_dev->mode & SPI_3WIRE) { /* MISO/MOSI signals shared */
+		/*
+		 * SPI_3WIRE and xfer->tx_buf != NULL and xfer->rx_buf != NULL
+		 * is forbidden und unvalidated by SPI subsystem so depending
+		 * on the valid buffer, we can determine the direction of the
+		 * transfer.
+		 */
+		mode = SPI_HALF_DUPLEX;
+		if (!transfer->tx_buf)
+			stm32_spi_clr_bits(spi, STM32_SPI_CR1, SPI_CR1_HDDIR);
+		else if (!transfer->rx_buf)
+			stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_HDDIR);
+	} else {
+		if (!transfer->tx_buf)
+			mode = SPI_SIMPLEX_RX;
+		else if (!transfer->rx_buf)
+			mode = SPI_SIMPLEX_TX;
+	}
+	if (spi->cur_comm != mode) {
+		spi->cur_comm = mode;
+
+		cfg2_clrb |= SPI_CFG2_COMM;
+		cfg2_setb |= (mode << SPI_CFG2_COMM_SHIFT) & SPI_CFG2_COMM;
+	}
+
+	cfg2_clrb |= SPI_CFG2_MIDI;
+	if ((transfer->len > 1) && (spi->cur_midi > 0)) {
+		u32 sck_period_ns = DIV_ROUND_UP(SPI_1HZ_NS, spi->cur_speed);
+		u32 midi = min((u32)DIV_ROUND_UP(spi->cur_midi, sck_period_ns),
+			       (u32)SPI_CFG2_MIDI >> SPI_CFG2_MIDI_SHIFT);
+
+		dev_dbg(spi->dev, "period=%dns, midi=%d(=%dns)\n",
+			sck_period_ns, midi, midi * sck_period_ns);
+
+		cfg2_setb |= (midi << SPI_CFG2_MIDI_SHIFT) & SPI_CFG2_MIDI;
+	}
+
+	if (cfg2_clrb || cfg2_setb)
+		writel_relaxed((readl_relaxed(spi->base + STM32_SPI_CFG2) &
+				~cfg2_clrb) | cfg2_setb,
+			       spi->base + STM32_SPI_CFG2);
+
+	nb_words = DIV_ROUND_UP(transfer->len * 8,
+				(spi->cur_bpw <= 8) ? 8 :
+				(spi->cur_bpw <= 16) ? 16 : 32);
+	nb_words <<= SPI_CR2_TSIZE_SHIFT;
+
+	if (nb_words <= SPI_CR2_TSIZE) {
+		writel_relaxed(nb_words, spi->base + STM32_SPI_CR2);
+	} else {
+		ret = -EMSGSIZE;
+		goto out;
+	}
+
+	spi->cur_xferlen = transfer->len;
+
+	dev_dbg(spi->dev, "transfer communication mode set to %d\n",
+		spi->cur_comm);
+	dev_dbg(spi->dev,
+		"data frame of %d-bit, data packet of %d data frames\n",
+		spi->cur_bpw, spi->cur_fthlv);
+	dev_dbg(spi->dev, "speed set to %dHz\n", spi->cur_speed);
+	dev_dbg(spi->dev, "transfer of %d bytes (%d data frames)\n",
+		spi->cur_xferlen, nb_words);
+	dev_dbg(spi->dev, "dma %s\n",
+		(spi->cur_usedma) ? "enabled" : "disabled");
+
+out:
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return ret;
+}
+
+/**
+ * stm32_spi_transfer_one - transfer a single spi_transfer
+ *
+ * It must return 0 if the transfer is finished or 1 if the transfer is still
+ * in progress.
+ */
+static int stm32_spi_transfer_one(struct spi_master *master,
+				  struct spi_device *spi_dev,
+				  struct spi_transfer *transfer)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	spi->tx_buf = transfer->tx_buf;
+	spi->rx_buf = transfer->rx_buf;
+	spi->tx_len = spi->tx_buf ? transfer->len : 0;
+	spi->rx_len = spi->rx_buf ? transfer->len : 0;
+
+	spi->cur_usedma = stm32_spi_can_dma(master, spi_dev, transfer);
+
+	ret = stm32_spi_transfer_one_setup(spi, spi_dev, transfer);
+	if (ret) {
+		dev_err(spi->dev, "SPI transfer setup failed\n");
+		return ret;
+	}
+
+	if (spi->cur_usedma)
+		return stm32_spi_transfer_one_dma(spi, transfer);
+	else
+		return stm32_spi_transfer_one_irq(spi);
+}
+
+/**
+ * stm32_spi_unprepare_msg - relax the hardware
+ *
+ * Normally, if TSIZE has been configured, we should relax the hardware at the
+ * reception of the EOT interrupt. But in case of error, EOT will not be
+ * raised. So the subsystem unprepare_message call allows us to properly
+ * complete the transfer from an hardware point of view.
+ */
+static int stm32_spi_unprepare_msg(struct spi_master *master,
+				   struct spi_message *msg)
+{
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	stm32_spi_disable(spi);
+
+	return 0;
+}
+
+/**
+ * stm32_spi_config - Configure SPI controller as SPI master
+ */
+static int stm32_spi_config(struct stm32_spi *spi)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&spi->lock, flags);
+
+	/* Ensure I2SMOD bit is kept cleared */
+	stm32_spi_clr_bits(spi, STM32_SPI_I2SCFGR, SPI_I2SCFGR_I2SMOD);
+
+	/*
+	 * - SS input value high
+	 * - transmitter half duplex direction
+	 * - automatic communication suspend when RX-Fifo is full
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CR1, SPI_CR1_SSI |
+					       SPI_CR1_HDDIR |
+					       SPI_CR1_MASRX);
+
+	/*
+	 * - Set the master mode (default Motorola mode)
+	 * - Consider 1 master/n slaves configuration and
+	 *   SS input value is determined by the SSI bit
+	 * - keep control of all associated GPIOs
+	 */
+	stm32_spi_set_bits(spi, STM32_SPI_CFG2, SPI_CFG2_MASTER |
+						SPI_CFG2_SSM |
+						SPI_CFG2_AFCNTR);
+
+	spin_unlock_irqrestore(&spi->lock, flags);
+
+	return 0;
+}
+
+static const struct of_device_id stm32_spi_of_match[] = {
+	{ .compatible = "st,stm32-spi", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stm32_spi_of_match);
+
+static int stm32_spi_probe(struct platform_device *pdev)
+{
+	struct spi_master *master;
+	struct stm32_spi *spi;
+	struct resource *res;
+	int i, ret;
+
+	master = spi_alloc_master(&pdev->dev, sizeof(struct stm32_spi));
+	if (!master) {
+		dev_err(&pdev->dev, "spi master allocation failed\n");
+		return -ENOMEM;
+	}
+	platform_set_drvdata(pdev, master);
+
+	spi = spi_master_get_devdata(master);
+	spi->dev = &pdev->dev;
+	spi->master = master;
+	spin_lock_init(&spi->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	spi->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(spi->base)) {
+		ret = PTR_ERR(spi->base);
+		goto err_master_put;
+	}
+	spi->phys_addr = (dma_addr_t)res->start;
+
+	spi->irq = platform_get_irq(pdev, 0);
+	if (spi->irq <= 0) {
+		dev_err(&pdev->dev, "no irq: %d\n", spi->irq);
+		ret = -ENOENT;
+		goto err_master_put;
+	}
+	ret = devm_request_threaded_irq(&pdev->dev, spi->irq, NULL,
+					stm32_spi_irq, IRQF_ONESHOT,
+					pdev->name, master);
+	if (ret) {
+		dev_err(&pdev->dev, "irq%d request failed: %d\n", spi->irq,
+			ret);
+		goto err_master_put;
+	}
+
+	spi->clk = devm_clk_get(&pdev->dev, 0);
+	if (IS_ERR(spi->clk)) {
+		ret = PTR_ERR(spi->clk);
+		dev_err(&pdev->dev, "clk get failed: %d\n", ret);
+		goto err_master_put;
+	}
+
+	ret = clk_prepare_enable(spi->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "clk enable failed: %d\n", ret);
+		goto err_master_put;
+	}
+	spi->clk_rate = clk_get_rate(spi->clk);
+	if (!spi->clk_rate) {
+		dev_err(&pdev->dev, "clk rate = 0\n");
+		ret = -EINVAL;
+		goto err_master_put;
+	}
+
+	spi->rst = devm_reset_control_get(&pdev->dev, NULL);
+	if (!IS_ERR(spi->rst)) {
+		reset_control_assert(spi->rst);
+		udelay(2);
+		reset_control_deassert(spi->rst);
+	}
+
+	spi->fifo_size = stm32_spi_get_fifo_size(spi);
+
+	ret = stm32_spi_config(spi);
+	if (ret) {
+		dev_err(&pdev->dev, "controller configuration failed: %d\n",
+			ret);
+		goto err_clk_disable;
+	}
+
+	master->dev.of_node = pdev->dev.of_node;
+	master->auto_runtime_pm = true;
+	master->bus_num = pdev->id;
+	master->mode_bits = SPI_MODE_3 | SPI_CS_HIGH | SPI_LSB_FIRST |
+			    SPI_3WIRE | SPI_LOOP;
+	master->bits_per_word_mask = stm32_spi_get_bpw_mask(spi);
+	master->max_speed_hz = spi->clk_rate / SPI_MBR_DIV_MIN;
+	master->min_speed_hz = spi->clk_rate / SPI_MBR_DIV_MAX;
+	master->setup = stm32_spi_setup;
+	master->prepare_message = stm32_spi_prepare_msg;
+	master->transfer_one = stm32_spi_transfer_one;
+	master->unprepare_message = stm32_spi_unprepare_msg;
+
+	spi->dma_tx = dma_request_slave_channel(spi->dev, "tx");
+	if (!spi->dma_tx)
+		dev_warn(&pdev->dev, "failed to request tx dma channel\n");
+	else
+		master->dma_tx = spi->dma_tx;
+
+	spi->dma_rx = dma_request_slave_channel(spi->dev, "rx");
+	if (!spi->dma_rx)
+		dev_warn(&pdev->dev, "failed to request rx dma channel\n");
+	else
+		master->dma_rx = spi->dma_rx;
+
+	if (spi->dma_tx || spi->dma_rx)
+		master->can_dma = stm32_spi_can_dma;
+
+	ret = devm_spi_register_master(&pdev->dev, master);
+	if (ret) {
+		dev_err(&pdev->dev, "spi master registration failed: %d\n",
+			ret);
+		goto err_dma_release;
+	}
+
+	if (!master->cs_gpios) {
+		dev_err(&pdev->dev, "no CS gpios available\n");
+		ret = -EINVAL;
+		goto err_dma_release;
+	}
+
+	for (i = 0; i < master->num_chipselect; i++) {
+		if (!gpio_is_valid(master->cs_gpios[i])) {
+			dev_err(&pdev->dev, "%i is not a valid gpio\n",
+				master->cs_gpios[i]);
+			ret = -EINVAL;
+			goto err_dma_release;
+		}
+
+		ret = devm_gpio_request(&pdev->dev, master->cs_gpios[i],
+					DRIVER_NAME);
+		if (ret) {
+			dev_err(&pdev->dev, "can't get CS gpio %i\n",
+				master->cs_gpios[i]);
+			goto err_dma_release;
+		}
+	}
+
+	dev_info(&pdev->dev, "driver initialized\n");
+
+	return 0;
+
+err_dma_release:
+	if (spi->dma_tx)
+		dma_release_channel(spi->dma_tx);
+	if (spi->dma_rx)
+		dma_release_channel(spi->dma_rx);
+err_clk_disable:
+	clk_disable_unprepare(spi->clk);
+err_master_put:
+	spi_master_put(master);
+
+	return ret;
+}
+
+static int stm32_spi_remove(struct platform_device *pdev)
+{
+	struct spi_master *master = platform_get_drvdata(pdev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+
+	stm32_spi_disable(spi);
+
+	if (master->dma_tx)
+		dma_release_channel(master->dma_tx);
+	if (master->dma_rx)
+		dma_release_channel(master->dma_rx);
+
+	clk_disable_unprepare(spi->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int stm32_spi_suspend(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = spi_master_suspend(master);
+	if (ret)
+		return ret;
+
+	clk_disable_unprepare(spi->clk);
+
+	return ret;
+}
+
+static int stm32_spi_resume(struct device *dev)
+{
+	struct spi_master *master = dev_get_drvdata(dev);
+	struct stm32_spi *spi = spi_master_get_devdata(master);
+	int ret;
+
+	ret = clk_prepare_enable(spi->clk);
+	if (ret)
+		return ret;
+	ret = spi_master_resume(master);
+	if (ret)
+		clk_disable_unprepare(spi->clk);
+
+	return ret;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(stm32_spi_pm_ops,
+			 stm32_spi_suspend, stm32_spi_resume);
+
+static struct platform_driver stm32_spi_driver = {
+	.probe = stm32_spi_probe,
+	.remove = stm32_spi_remove,
+	.driver = {
+		.name = DRIVER_NAME,
+		.pm = &stm32_spi_pm_ops,
+		.of_match_table = stm32_spi_of_match,
+	},
+};
+
+module_platform_driver(stm32_spi_driver);
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+MODULE_DESCRIPTION("STMicroelectronics STM32 SPI Controller driver");
+MODULE_AUTHOR("Amelie Delaunay <amelie.delaunay@st.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.11.0