Re: [PATCH 1/8] gpio: Add Elba SoC gpio driver for spi cs control
From: Brad Larson
Date: Mon Oct 04 2021 - 12:47:31 EST
On Sun, Aug 29, 2021 at 2:09 PM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
>
> On Mon, Aug 23, 2021 at 3:06 AM Brad Larson <brad@xxxxxxxxxxx> wrote:
>
> > The gpio pins being used for the Elba SoC SPI CS are dedicated to this
> > function. Are you recommending that the code in
> > drivers/gpio/gpio-elba-spics.c be integrated into
> > drivers/spi/spi-dw-mmio.c?
>
> That makes most sense does it not?
>
> Special purpose pins should be managed by that special purpose
> hardware driver, DW SPI in this case.
>
> The compatible string etc should be enough to determine that we
> need some extra GPIO control here, possibly specify extra registers
> for the SPI host etc.
>
> The struct spi_master has a special callback .set_cs() and you
> should make this behave special for your special hardware.
> In the case of the DW driver it appears that even subdrivers can
> pass a custom version of this call in struct dw_spi.
>
> Yours,
> Linus Walleij
Yes that works, please see the diff below where the file
gpio-elba-spics.c goes away. The original implementation was
motivated by gpio-spear-spics.c.
Best,
Brad
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index d3b509e175e47..14751c7ccd1f4 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -240,11 +240,6 @@ config GPIO_EIC_SPRD
help
Say yes here to support Spreadtrum EIC device.
-config GPIO_ELBA_SPICS
- bool "Pensando Elba SoC SPI Chip Select as GPIO support"
- depends on ARCH_PENSANDO_ELBA_SOC
- def_bool y
-
config GPIO_EM
tristate "Emma Mobile GPIO"
depends on (ARCH_EMEV2 || COMPILE_TEST) && OF_GPIO
diff --git a/arch/arm64/boot/dts/pensando/elba-asic-common.dtsi
b/arch/arm64/boot/dts/pensando/elba-asic-common.dtsi
index a59405dc5676d..17dfb0c91f84c 100644
--- a/arch/arm64/boot/dts/pensando/elba-asic-common.dtsi
+++ b/arch/arm64/boot/dts/pensando/elba-asic-common.dtsi
@@ -66,8 +66,8 @@
&spi0 {
num-cs = <4>;
- cs-gpios = <&spics 0 GPIO_ACTIVE_LOW>, <&spics 1 GPIO_ACTIVE_LOW>,
- <&porta 1 GPIO_ACTIVE_LOW>, <&porta 7 GPIO_ACTIVE_LOW>;
+ cs-gpios = <0>, <0>,
+ <&porta 1 GPIO_ACTIVE_LOW>, <&porta 7 GPIO_ACTIVE_LOW>;
status = "okay";
spi0_cs0@0 {
compatible = "pensando,cpld";
diff --git a/arch/arm64/boot/dts/pensando/elba.dtsi
b/arch/arm64/boot/dts/pensando/elba.dtsi
index 029dd5f0045f3..3ff4c39815639 100644
--- a/arch/arm64/boot/dts/pensando/elba.dtsi
+++ b/arch/arm64/boot/dts/pensando/elba.dtsi
@@ -127,6 +127,7 @@
spi0: spi@2800 {
compatible = "pensando,elba-spi";
reg = <0x0 0x2800 0x0 0x100>;
+ pensando,spics = <&mssoc 0x2468 0>;
clocks = <&ahb_clk>;
interrupts = <GIC_SPI 9 IRQ_TYPE_LEVEL_HIGH>;
#address-cells = <1>;
@@ -257,13 +258,6 @@
reg = <0x0 0x307c2080 0x0 0x4>;
};
- spics: spics@307c2468 {
- compatible = "pensando,elba-spics";
- reg = <0x0 0x307c2468 0x0 0x4>;
- gpio-controller;
- #gpio-cells = <2>;
- };
-
pcie@307c2480 {
compatible = "pensando,pcie";
reg = <0x0 0x307c2480 0x0 0x4 /* MS CFG_WDT */
diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 3379720cfcb8..64644bae8923 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -16,6 +16,7 @@
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
+#include <linux/gpio.h>
#include <linux/acpi.h>
#include <linux/property.h>
#include <linux/regmap.h>
@@ -53,6 +54,24 @@ struct dw_spi_mscc {
void __iomem *spi_mst; /* Not sparx5 */
};
+struct dw_spi_elba {
+ struct regmap *regmap;
+ unsigned int reg;
+ unsigned int ctl;
+};
+
+/*
+ * ctl: 1 | 0
+ * cs: 1 0 | 1 0
+ * bit: 7-------6-------5-------4---|---3-------2-------1-------0
+ * cs1 cs1_ovr cs0 cs0_ovr| cs1 cs1_ovr cs0 cs0_ovr
+ * ssi1 | ssi0
+ */
+#define ELBA_SPICS_SHIFT(ctl, cs) (4 * (ctl) + 2 * (cs))
+#define ELBA_SPICS_MASK(ctl, cs) (0x3 << ELBA_SPICS_SHIFT(ctl, cs))
+#define ELBA_SPICS_SET(ctl, cs, val) \
+ ((((val) << 1) | 0x1) << ELBA_SPICS_SHIFT(ctl, cs))
+
/*
* The Designware SPI controller (referred to as master in the documentation)
* automatically deasserts chip select when the tx fifo is empty. The chip
@@ -237,6 +256,74 @@ static int dw_spi_canaan_k210_init(struct
platform_device *pdev,
return 0;
}
+static void elba_spics_set_cs(struct dw_spi_elba *dwselba, int cs, int enable)
+{
+ regmap_update_bits(dwselba->regmap, dwselba->reg,
+ ELBA_SPICS_MASK(dwselba->ctl, cs),
+ ELBA_SPICS_SET(dwselba->ctl, cs, enable));
+}
+
+static void dw_spi_elba_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_elba *dwselba = dwsmmio->priv;
+ u8 cs = spi->chip_select;
+
+ if (cs < 2) {
+ /* overridden native chip-select */
+ elba_spics_set_cs(dwselba, spi->chip_select, enable);
+ }
+
+ /*
+ * The DW SPI controller needs a native CS bit selected to start
+ * the serial engine, and we have fewer native CSs than we need, so
+ * use CS0 always.
+ */
+ spi->chip_select = 0;
+ dw_spi_set_cs(spi, enable);
+ spi->chip_select = cs;
+}
+
+static int dw_spi_elba_init(struct platform_device *pdev,
+ struct dw_spi_mmio *dwsmmio)
+{
+ struct of_phandle_args args;
+ struct dw_spi_elba *dwselba;
+ struct regmap *regmap;
+ int rc;
+
+ rc = of_parse_phandle_with_fixed_args(pdev->dev.of_node,
+ "pensando,spics", 2, 0, &args);
+ if (rc) {
+ dev_err(&pdev->dev, "could not find pensando,spics\n");
+ return rc;
+ }
+
+ regmap = syscon_node_to_regmap(args.np);
+ if (IS_ERR(regmap)) {
+ dev_err(&pdev->dev, "could not map pensando,spics\n");
+ return PTR_ERR(regmap);
+ }
+
+ dwselba = devm_kzalloc(&pdev->dev, sizeof(*dwselba), GFP_KERNEL);
+ if (!dwselba)
+ return -ENOMEM;
+
+ dwselba->regmap = regmap;
+ dwselba->reg = args.args[0];
+ dwselba->ctl = args.args[1];
+
+ /* deassert cs */
+ elba_spics_set_cs(dwselba, 0, 1);
+ elba_spics_set_cs(dwselba, 1, 1);
+
+ dwsmmio->priv = dwselba;
+ dwsmmio->dws.set_cs = dw_spi_elba_set_cs;
+
+ return 0;
+}
+
static int dw_spi_mmio_probe(struct platform_device *pdev)
{
int (*init_func)(struct platform_device *pdev,
@@ -351,6 +438,7 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {
{ .compatible = "intel,keembay-ssi", .data = dw_spi_keembay_init},
{ .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
{ .compatible = "canaan,k210-spi", dw_spi_canaan_k210_init},
+ { .compatible = "pensando,elba-spi", .data = dw_spi_elba_init},
{ /* end of table */}
};
MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);