[PATCH v2 0/4] Add support for MSCC Ocelot SPI

[PATCH v2 0/4] Add support for MSCC Ocelot SPI

[Alexandre Belloni]

Hello,

The MSCC MIPS SoC line uses a designware IP for the SPI controller but
still requires some special handling to give control of the SPI
interface to the IP and also has a specific handling for the chip
select.

Changes in v2:
 - Removed already applied patches
 - separated DT binding changes from the driver patch

Alexandre Belloni (4):
  dt-bindings: spi: snps,dw-apb-ssi: document Microsemi integration
  spi: dw-mmio: add MSCC Ocelot support
  mips: dts: mscc: Add spi on Ocelot
  mips: dts: mscc: enable spi and NOR flash support on ocelot PCB123

 arch/mips/boot/dts/mscc/ocelot.dtsi       | 11 +++
 arch/mips/boot/dts/mscc/ocelot_pcb123.dts | 10 +++
 drivers/spi/spi-dw-mmio.c                 | 91 +++++++++++++++++++++++
 3 files changed, 112 insertions(+)

-- 
2.18.0

[PATCH v2 1/4] dt-bindings: spi: snps,dw-apb-ssi: document Microsemi integration

[Alexandre Belloni]

The integration of the Designware SPI controller on Microsemi SoCs requires
an extra register set to be able to give the IP control of the SPI
interface.

Cc: Rob Herring <robh+dt@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index 204b311e0400..d97b9fc4c1cb 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -1,8 +1,9 @@
 Synopsys DesignWare AMBA 2.0 Synchronous Serial Interface.
 
 Required properties:
-- compatible : "snps,dw-apb-ssi"
-- reg : The register base for the controller.
+- compatible : "snps,dw-apb-ssi" or "mscc,<soc>-spi"
+- reg : The register base for the controller. For "mscc,<soc>-spi", a second
+  register set is required (named ICPU_CFG:SPI_MST)
 - interrupts : One interrupt, used by the controller.
 - #address-cells : <1>, as required by generic SPI binding.
 - #size-cells : <0>, also as required by generic SPI binding.
-- 
2.18.0

[PATCH v2 2/4] spi: dw-mmio: add MSCC Ocelot support

[Alexandre Belloni]

Because the SPI controller deasserts the chip select when the TX fifo is
empty (which may happen in the middle of a transfer), the CS should be
handled by linux. Unfortunately, some or all of the first four chip
selects are not muxable as GPIOs, depending on the SoC.

There is a way to bitbang those pins by using the SPI boot controller so
use it to set the chip selects.

At init time, it is also necessary to give control of the SPI interface to
the Designware IP.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---

Change in v2:
 - correctly use device_get_match_data to retrieve the init function instead of
   hardcoding it.

 .../bindings/spi/snps,dw-apb-ssi.txt          |  5 +-
 drivers/spi/spi-dw-mmio.c                     | 91 +++++++++++++++++++
 2 files changed, 93 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
index d97b9fc4c1cb..204b311e0400 100644
--- a/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
+++ b/Documentation/devicetree/bindings/spi/snps,dw-apb-ssi.txt
@@ -1,9 +1,8 @@
 Synopsys DesignWare AMBA 2.0 Synchronous Serial Interface.
 
 Required properties:
-- compatible : "snps,dw-apb-ssi" or "mscc,<soc>-spi"
-- reg : The register base for the controller. For "mscc,<soc>-spi", a second
-  register set is required (named ICPU_CFG:SPI_MST)
+- compatible : "snps,dw-apb-ssi"
+- reg : The register base for the controller.
 - interrupts : One interrupt, used by the controller.
 - #address-cells : <1>, as required by generic SPI binding.
 - #size-cells : <0>, also as required by generic SPI binding.
diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index d25cc4037e23..0bc47545c49c 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -15,11 +15,13 @@
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/scatterlist.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_gpio.h>
 #include <linux/of_platform.h>
 #include <linux/property.h>
+#include <linux/regmap.h>
 
 #include "spi-dw.h"
 
@@ -28,10 +30,91 @@
 struct dw_spi_mmio {
 	struct dw_spi  dws;
 	struct clk     *clk;
+	void           *priv;
 };
 
+#define MSCC_CPU_SYSTEM_CTRL_GENERAL_CTRL	0x24
+#define OCELOT_IF_SI_OWNER_MASK			GENMASK(5, 4)
+#define OCELOT_IF_SI_OWNER_OFFSET		4
+#define MSCC_IF_SI_OWNER_SISL			0
+#define MSCC_IF_SI_OWNER_SIBM			1
+#define MSCC_IF_SI_OWNER_SIMC			2
+
+#define MSCC_SPI_MST_SW_MODE			0x14
+#define MSCC_SPI_MST_SW_MODE_SW_PIN_CTRL_MODE	BIT(13)
+#define MSCC_SPI_MST_SW_MODE_SW_SPI_CS(x)	(x << 5)
+struct dw_spi_mscc {
+	struct regmap       *syscon;
+	void __iomem        *spi_mst;
+};
+
+/*
+ * The SPI master controller automatically deasserts
+ * chip select when the tx fifo is empty. The chip selects then needs to be
+ * either driven as GPIOs or, for the first 4 using the the SPI boot controller
+ * registers. the final chip select is an OR gate between the SPI master
+ * controller and the SPI boot controller.
+ */
+static void dw_spi_mscc_set_cs(struct spi_device *spi, bool enable)
+{
+	struct dw_spi *dws = spi_master_get_devdata(spi->master);
+	struct dw_spi_mmio *dwsmmio = container_of(dws, struct dw_spi_mmio, dws);
+	struct dw_spi_mscc *dwsmscc = dwsmmio->priv;
+	u32 cs = spi->chip_select;
+
+	if (cs < 4) {
+		u32 sw_mode = MSCC_SPI_MST_SW_MODE_SW_PIN_CTRL_MODE;
+
+		if (!enable)
+			sw_mode |= MSCC_SPI_MST_SW_MODE_SW_SPI_CS(BIT(cs));
+
+		writel(sw_mode, dwsmscc->spi_mst + MSCC_SPI_MST_SW_MODE);
+	}
+
+	if (!enable)
+		dw_writel(dws, DW_SPI_SER, BIT(cs));
+}
+
+static int dw_spi_mscc_init(struct platform_device *pdev,
+			    struct dw_spi_mmio *dwsmmio)
+{
+	struct dw_spi_mscc *dwsmscc;
+	struct resource *res;
+
+	dwsmscc = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_mscc),
+			       GFP_KERNEL);
+	if (!dwsmscc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	dwsmscc->spi_mst = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(dwsmscc->spi_mst)) {
+		dev_err(&pdev->dev, "SPI_MST region map failed\n");
+		return PTR_ERR(dwsmscc->spi_mst);
+	}
+
+	dwsmscc->syscon = syscon_regmap_lookup_by_compatible("mscc,ocelot-cpu-syscon");
+	if (IS_ERR(dwsmscc->syscon))
+		return PTR_ERR(dwsmscc->syscon);
+
+	/* Deassert all CS */
+	writel(0, dwsmscc->spi_mst + MSCC_SPI_MST_SW_MODE);
+
+	/* Select the owner of the SI interface */
+	regmap_update_bits(dwsmscc->syscon, MSCC_CPU_SYSTEM_CTRL_GENERAL_CTRL,
+			   OCELOT_IF_SI_OWNER_MASK,
+			   MSCC_IF_SI_OWNER_SIMC << OCELOT_IF_SI_OWNER_OFFSET);
+
+	dwsmmio->dws.set_cs = dw_spi_mscc_set_cs;
+	dwsmmio->priv = dwsmscc;
+
+	return 0;
+}
+
 static int dw_spi_mmio_probe(struct platform_device *pdev)
 {
+	int (*init_func)(struct platform_device *pdev,
+			 struct dw_spi_mmio *dwsmmio);
 	struct dw_spi_mmio *dwsmmio;
 	struct dw_spi *dws;
 	struct resource *mem;
@@ -99,6 +182,13 @@ static int dw_spi_mmio_probe(struct platform_device *pdev)
 		}
 	}
 
+	init_func = device_get_match_data(&pdev->dev);
+	if (init_func) {
+		ret = init_func(pdev, dwsmmio);
+		if (ret)
+			goto out;
+	}
+
 	ret = dw_spi_add_host(&pdev->dev, dws);
 	if (ret)
 		goto out;
@@ -123,6 +213,7 @@ static int dw_spi_mmio_remove(struct platform_device *pdev)
 
 static const struct of_device_id dw_spi_mmio_of_match[] = {
 	{ .compatible = "snps,dw-apb-ssi", },
+	{ .compatible = "mscc,ocelot-spi", .data = dw_spi_mscc_init},
 	{ /* end of table */}
 };
 MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);
-- 
2.18.0

Re: [PATCH v2 2/4] spi: dw-mmio: add MSCC Ocelot support

[Andy Shevchenko]

On Fri, Jul 27, 2018 at 3:05 PM, Alexandre Belloni
<alexandre.belloni@bootlin.com> wrote:
> Because the SPI controller deasserts the chip select when the TX fifo is
> empty (which may happen in the middle of a transfer), the CS should be
> handled by linux. Unfortunately, some or all of the first four chip
> selects are not muxable as GPIOs, depending on the SoC.
>
> There is a way to bitbang those pins by using the SPI boot controller so
> use it to set the chip selects.
>
> At init time, it is also necessary to give control of the SPI interface to
> the Designware IP.

Thanks for an update! My comments below (most of them just about style).

First of all, can we use 'controller' over the 'master' in the code?

>  .../bindings/spi/snps,dw-apb-ssi.txt          |  5 +-

>  Required properties:
> -- compatible : "snps,dw-apb-ssi" or "mscc,<soc>-spi"
> -- reg : The register base for the controller. For "mscc,<soc>-spi", a second
> -  register set is required (named ICPU_CFG:SPI_MST)
> +- compatible : "snps,dw-apb-ssi"
> +- reg : The register base for the controller.

This hunk is odd.

>  struct dw_spi_mmio {
>         struct dw_spi  dws;
>         struct clk     *clk;
> +       void           *priv;
>  };

> +#define MSCC_SPI_MST_SW_MODE                   0x14
> +#define MSCC_SPI_MST_SW_MODE_SW_PIN_CTRL_MODE  BIT(13)
> +#define MSCC_SPI_MST_SW_MODE_SW_SPI_CS(x)      (x << 5)

+ blank line ?

> +struct dw_spi_mscc {
> +       struct regmap       *syscon;

> +       void __iomem        *spi_mst;

A nit: do we need to repeat "spi" here?

> +};

> +       if (!enable)
> +               dw_writel(dws, DW_SPI_SER, BIT(cs));

This sounds like

dw_set_cs(spi, enable);

> +       dwsmscc = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_mscc),
> +                              GFP_KERNEL);

sizeof(*dwsmcc)  and one line in the result?

> +       /* Deassert all CS */
> +       writel(0, dwsmscc->spi_mst + MSCC_SPI_MST_SW_MODE);

Hmm... Don't we need to call dw_set_cs() for all of them as well?
If yes, perhaps better to call custom set_cs() in a loop?

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v2 2/4] spi: dw-mmio: add MSCC Ocelot support

[Alexandre Belloni]

On 27/07/2018 16:07:54+0300, Andy Shevchenko wrote:
> On Fri, Jul 27, 2018 at 3:05 PM, Alexandre Belloni
> <alexandre.belloni@bootlin.com> wrote:
> > Because the SPI controller deasserts the chip select when the TX fifo is
> > empty (which may happen in the middle of a transfer), the CS should be
> > handled by linux. Unfortunately, some or all of the first four chip
> > selects are not muxable as GPIOs, depending on the SoC.
> >
> > There is a way to bitbang those pins by using the SPI boot controller so
> > use it to set the chip selects.
> >
> > At init time, it is also necessary to give control of the SPI interface to
> > the Designware IP.
> 
> Thanks for an update! My comments below (most of them just about style).
> 
> First of all, can we use 'controller' over the 'master' in the code?
> 
> >  .../bindings/spi/snps,dw-apb-ssi.txt          |  5 +-
> 
> >  Required properties:
> > -- compatible : "snps,dw-apb-ssi" or "mscc,<soc>-spi"
> > -- reg : The register base for the controller. For "mscc,<soc>-spi", a second
> > -  register set is required (named ICPU_CFG:SPI_MST)
> > +- compatible : "snps,dw-apb-ssi"
> > +- reg : The register base for the controller.
> 
> This hunk is odd.
> 

Indeed, I'm not exactly sure what happened. I'll make sure it is
removed.

> >  struct dw_spi_mmio {
> >         struct dw_spi  dws;
> >         struct clk     *clk;
> > +       void           *priv;
> >  };
> 
> > +#define MSCC_SPI_MST_SW_MODE                   0x14
> > +#define MSCC_SPI_MST_SW_MODE_SW_PIN_CTRL_MODE  BIT(13)
> > +#define MSCC_SPI_MST_SW_MODE_SW_SPI_CS(x)      (x << 5)
> 
> + blank line ?
> 
> > +struct dw_spi_mscc {
> > +       struct regmap       *syscon;
> 
> > +       void __iomem        *spi_mst;
> 
> A nit: do we need to repeat "spi" here?
> 

The register set is named SPI_MST in the datasheet so I would prefer
keeping it that way. I don't think this is an issue as it is MSCC
specific anyway.
The SI interface can be controlled by three different IPs, their name in
the datasheet are SPI boot, SPI slave and SPI master. The DW IP in what
is referred to as SPI master. The two other IPs can't be used under
linux.

So I'd like to keep spi_mst in the defines and variable but I can
probably tweak the comment to avoid the confusion.

> > +};
> 
> > +       if (!enable)
> > +               dw_writel(dws, DW_SPI_SER, BIT(cs));
> 
> This sounds like
> 
> dw_set_cs(spi, enable);
> 

That's right, I can probably use dw_spi_set_cs here

> > +       dwsmscc = devm_kzalloc(&pdev->dev, sizeof(struct dw_spi_mscc),
> > +                              GFP_KERNEL);
> 
> sizeof(*dwsmcc)  and one line in the result?
> 
> > +       /* Deassert all CS */
> > +       writel(0, dwsmscc->spi_mst + MSCC_SPI_MST_SW_MODE);
> 
> Hmm... Don't we need to call dw_set_cs() for all of them as well?
> If yes, perhaps better to call custom set_cs() in a loop?
> 

Most likely not, for the same reason why the common code is not doing
it. The FIFO is definitively empty so the CS will be unset.


-- 
Alexandre Belloni, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

[PATCH v2 3/4] mips: dts: mscc: Add spi on Ocelot

[Alexandre Belloni]

Add support for the SPI controller

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 arch/mips/boot/dts/mscc/ocelot.dtsi | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/mips/boot/dts/mscc/ocelot.dtsi b/arch/mips/boot/dts/mscc/ocelot.dtsi
index 4f33dbc67348..f7616a476247 100644
--- a/arch/mips/boot/dts/mscc/ocelot.dtsi
+++ b/arch/mips/boot/dts/mscc/ocelot.dtsi
@@ -91,6 +91,17 @@
 			status = "disabled";
 		};
 
+		spi: spi@101000 {
+			compatible = "mscc,ocelot-spi", "snps,dw-apb-ssi";
+			#address-cells = <1>;
+			#size-cells = <0>;
+			reg = <0x101000 0x100>, <0x3c 0x18>;
+			interrupts = <9>;
+			clocks = <&ahb_clk>;
+
+			status = "disabled";
+		};
+
 		switch@1010000 {
 			compatible = "mscc,vsc7514-switch";
 			reg = <0x1010000 0x10000>,
-- 
2.18.0

[PATCH v2 4/4] mips: dts: mscc: enable spi and NOR flash support on ocelot PCB123

[Alexandre Belloni]

Ocelot PCB123 has a SPI NOR connected on its SPI bus.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
 arch/mips/boot/dts/mscc/ocelot_pcb123.dts | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/mips/boot/dts/mscc/ocelot_pcb123.dts b/arch/mips/boot/dts/mscc/ocelot_pcb123.dts
index 4ccd65379059..2266027759f9 100644
--- a/arch/mips/boot/dts/mscc/ocelot_pcb123.dts
+++ b/arch/mips/boot/dts/mscc/ocelot_pcb123.dts
@@ -26,6 +26,16 @@
 	status = "okay";
 };
 
+&spi {
+	status = "okay";
+
+	flash@0 {
+		compatible = "macronix,mx25l25635f", "jedec,spi-nor";
+		spi-max-frequency = <20000000>;
+		reg = <0>;
+	};
+};
+
 &mdio0 {
 	status = "okay";
 };
-- 
2.18.0