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Subject[PATCH v5 2/6] spi: dw: Add Microchip Sparx5 support
Date
This adds SPI support for the Sparx5 SoC, which is using the MMIO
Designware SPI controller.

The Sparx5 differs from the Ocelot version in these areas:

* The CS override is controlled by a new set of registers for
this purpose.

* The Sparx5 SPI controller has the RX sample delay register, and it
must be configured for the (SPI NAND) device on SPI2.

* The Sparx5 SPI controller has 2 different SPI bus interfaces on the
same controller (don't ask...). The "spi-mux" driver should be used
in conjunction with the SPI driver to select the appropriate bus.

Signed-off-by: Lars Povlsen <lars.povlsen@microchip.com>
---
drivers/spi/spi-dw-mmio.c | 70 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 69 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 403403deae66..18772c0c9220 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -45,6 +45,9 @@ struct dw_spi_mmio {
#define MSCC_SPI_MST_SW_MODE_SW_PIN_CTRL_MODE BIT(13)
#define MSCC_SPI_MST_SW_MODE_SW_SPI_CS(x) (x << 5)

+#define SPARX5_FORCE_ENA 0xa4
+#define SPARX5_FORCE_VAL 0xa8
+
/*
* For Keem Bay, CTRLR0[31] is used to select controller mode.
* 0: SSI is slave
@@ -54,7 +57,7 @@ struct dw_spi_mmio {

struct dw_spi_mscc {
struct regmap *syscon;
- void __iomem *spi_mst;
+ void __iomem *spi_mst; /* Not sparx5 */
};

/*
@@ -134,6 +137,70 @@ static int dw_spi_mscc_jaguar2_init(struct platform_device *pdev,
JAGUAR2_IF_SI_OWNER_OFFSET);
}

+/*
+ * The Designware SPI controller (referred to as master in the
+ * documentation) automatically deasserts chip select when the tx fifo
+ * is empty. The chip selects then needs to be driven by a CS override
+ * register. enable is an active low signal.
+ */
+static void dw_spi_sparx5_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;
+ u8 cs = spi->chip_select;
+
+ if (!enable) {
+ /* CS override drive enable */
+ regmap_write(dwsmscc->syscon, SPARX5_FORCE_ENA, 1);
+ /* Now set CSx enabled */
+ regmap_write(dwsmscc->syscon, SPARX5_FORCE_VAL, ~BIT(cs));
+ /* Allow settle */
+ usleep_range(1, 5);
+ } else {
+ /* CS value */
+ regmap_write(dwsmscc->syscon, SPARX5_FORCE_VAL, ~0);
+ /* Allow settle */
+ usleep_range(1, 5);
+ /* CS override drive disable */
+ regmap_write(dwsmscc->syscon, SPARX5_FORCE_ENA, 0);
+ }
+
+ dw_spi_set_cs(spi, enable);
+}
+
+static int dw_spi_mscc_sparx5_init(struct platform_device *pdev,
+ struct dw_spi_mmio *dwsmmio)
+{
+ const char *syscon_name = "microchip,sparx5-cpu-syscon";
+ struct device *dev = &pdev->dev;
+ struct dw_spi_mscc *dwsmscc;
+
+ if (!IS_ENABLED(CONFIG_SPI_MUX)) {
+ dev_err(dev, "This driver needs CONFIG_SPI_MUX\n");
+ return -EOPNOTSUPP;
+ }
+
+ dwsmscc = devm_kzalloc(dev, sizeof(*dwsmscc), GFP_KERNEL);
+ if (!dwsmscc)
+ return -ENOMEM;
+
+ dwsmscc->syscon =
+ syscon_regmap_lookup_by_compatible(syscon_name);
+ if (IS_ERR(dwsmscc->syscon)) {
+ dev_err(dev, "No syscon map %s\n", syscon_name);
+ return PTR_ERR(dwsmscc->syscon);
+ }
+
+ dwsmmio->dws.set_cs = dw_spi_sparx5_set_cs;
+ dwsmmio->priv = dwsmscc;
+
+ /* Register hook to configure CTRLR0 */
+ dwsmmio->dws.update_cr0 = dw_spi_update_cr0;
+
+ return 0;
+}
+
static int dw_spi_alpine_init(struct platform_device *pdev,
struct dw_spi_mmio *dwsmmio)
{
@@ -297,6 +364,7 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {
{ .compatible = "renesas,rzn1-spi", .data = dw_spi_dw_apb_init},
{ .compatible = "snps,dwc-ssi-1.01a", .data = dw_spi_dwc_ssi_init},
{ .compatible = "intel,keembay-ssi", .data = dw_spi_keembay_init},
+ { .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
{ /* end of table */}
};
MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);
--
2.27.0
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