spi: dw: Add support for multiple CTRLR0 layouts

CTRLR0 can have several different layouts depending on the specific device
(dw-apb-ssi vs dwc-ssi), and specific parameters set during synthesis.
Update the driver to support three specific configurations: dw-apb-ssi with
SSI_MAX_XFER_SIZE=16, dw-apb-ssi with SSI_MAX_XFER_SIZE=32, and dwc-ssi.

dw-apb-ssi is the version of the device on Altera/Intel SoCFPGAs, MSCC
SoCs, and Canaan Kendryte K210 SoCs. This is the only version this driver
supported before this change. The register layout before version 3.23a is:

|   31 .. 16  |
| other stuff |

|   15 .. 10  | 9 .. 8 | 7 .. 6 | 5 .. 4 | 3 .. 0 |
| other stuff |  TMOD  |  MODE  |  FRF   |  DFS   |

Note that DFS (Data Frame Size) is only 4 bits, limiting transfers to data
frames of 16 bits or less.

In version 3.23a, the SSI_MAX_XFER_SIZE parameter was introduced. This
parameter defaults to 16 (resulting in the same layout as prior versions),
but may also be set to 32. To allow setting longer data frame sizes, a new
DFS_32 register was introduced:

|   31 .. 21  | 20 .. 16 |
| other stuff |  DFS_32  |

|   15 .. 10  | 9 .. 8 | 7 .. 6 | 5 .. 4 |  3 .. 0   |
| other stuff |  TMOD  |  MODE  |  FRF   | all zeros |

The old DFS field no longer controls the data frame size. To detect this
layout, we try writing 0xF to DFS. If we read back 0x0, then this device
has SSI_MAX_XFER_SIZE=32.

dwc-ssi is the version of the device on Intel Keem Bay SoCs and Canaan
Kendryte K210 SoCs. The layout of ctrlr0 is:

|   31 .. 16  |
| other stuff |

|   15 .. 12  | 11 .. 10 | 9 .. 8 | 7 .. 6 | 4 .. 0 |
| other stuff |   TMOD   |  MODE  |  FRF   | DFS_32 |

The semantics of the fields have not changed since the previous version.
However, SSI_MAX_XFER_SIZE is effectively always 32.

To support these different layouts, we model our approach on the one
which the Linux kernel has taken. During probe, the driver calls an init
function stored in driver_data. This init function is responsible for
determining the layout of CTRLR0, and supplying the update_cr0 function.

The style of and information behind this commit is based on the Linux MMIO
driver for these devices. Specific reference was made to the series adding
support for Intel Keem Bay SoCs [1].

[1] https://lore.kernel.org/linux-spi/20200505130618.554-1-wan.ahmad.zainie.wan.mohamad@intel.com/

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

1 files changed, 149 insertions, 35 deletions

diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
index 0ebd2cf3cb..9e02fce6c6 100644
--- a/drivers/spi/designware_spi.c
+++ b/drivers/spi/designware_spi.c
@@ -3,6 +3,7 @@
  * Designware master SPI core controller driver
  *
  * Copyright (C) 2014 Stefan Roese <sr@denx.de>
+ * Copyright (C) 2020 Sean Anderson <seanga2@gmail.com>
  *
  * Very loosely based on the Linux driver:
  * drivers/spi/spi-dw.c, which is:
@@ -22,6 +23,7 @@
 #include <reset.h>
 #include <dm/device_compat.h>
 #include <linux/bitops.h>
+#include <linux/bitfield.h>
 #include <linux/compat.h>
 #include <linux/iopoll.h>
 #include <asm/io.h>
@@ -54,28 +56,48 @@
 #define DW_SPI_DR			0x60
 
 /* Bit fields in CTRLR0 */
-#define SPI_DFS_OFFSET			0
-
-#define SPI_FRF_OFFSET			4
-#define SPI_FRF_SPI			0x0
-#define SPI_FRF_SSP			0x1
-#define SPI_FRF_MICROWIRE		0x2
-#define SPI_FRF_RESV			0x3
-
-#define SPI_MODE_OFFSET			6
-#define SPI_SCPH_OFFSET			6
-#define SPI_SCOL_OFFSET			7
-
-#define SPI_TMOD_OFFSET			8
-#define SPI_TMOD_MASK			(0x3 << SPI_TMOD_OFFSET)
-#define	SPI_TMOD_TR			0x0		/* xmit & recv */
-#define SPI_TMOD_TO			0x1		/* xmit only */
-#define SPI_TMOD_RO			0x2		/* recv only */
-#define SPI_TMOD_EPROMREAD		0x3		/* eeprom read mode */
-
-#define SPI_SLVOE_OFFSET		10
-#define SPI_SRL_OFFSET			11
-#define SPI_CFS_OFFSET			12
+/*
+ * Only present when SSI_MAX_XFER_SIZE=16. This is the default, and the only
+ * option before version 3.23a.
+ */
+#define CTRLR0_DFS_MASK			GENMASK(3, 0)
+
+#define CTRLR0_FRF_MASK			GENMASK(5, 4)
+#define CTRLR0_FRF_SPI			0x0
+#define CTRLR0_FRF_SSP			0x1
+#define CTRLR0_FRF_MICROWIRE		0x2
+#define CTRLR0_FRF_RESV			0x3
+
+#define CTRLR0_MODE_MASK		GENMASK(7, 6)
+#define CTRLR0_MODE_SCPH		0x1
+#define CTRLR0_MODE_SCPOL		0x2
+
+#define CTRLR0_TMOD_MASK		GENMASK(9, 8)
+#define	CTRLR0_TMOD_TR			0x0		/* xmit & recv */
+#define CTRLR0_TMOD_TO			0x1		/* xmit only */
+#define CTRLR0_TMOD_RO			0x2		/* recv only */
+#define CTRLR0_TMOD_EPROMREAD		0x3		/* eeprom read mode */
+
+#define CTRLR0_SLVOE_OFFSET		10
+#define CTRLR0_SRL_OFFSET		11
+#define CTRLR0_CFS_MASK			GENMASK(15, 12)
+
+/* Only present when SSI_MAX_XFER_SIZE=32 */
+#define CTRLR0_DFS_32_MASK		GENMASK(20, 16)
+
+/* The next field is only present on versions after 4.00a */
+#define CTRLR0_SPI_FRF_MASK		GENMASK(22, 21)
+#define CTRLR0_SPI_FRF_BYTE		0x0
+#define	CTRLR0_SPI_FRF_DUAL		0x1
+#define	CTRLR0_SPI_FRF_QUAD		0x2
+
+/* Bit fields in CTRLR0 based on DWC_ssi_databook.pdf v1.01a */
+#define DWC_SSI_CTRLR0_DFS_MASK		GENMASK(4, 0)
+#define DWC_SSI_CTRLR0_FRF_MASK		GENMASK(7, 6)
+#define DWC_SSI_CTRLR0_MODE_MASK	GENMASK(9, 8)
+#define DWC_SSI_CTRLR0_TMOD_MASK	GENMASK(11, 10)
+#define DWC_SSI_CTRLR0_SRL_OFFSET	13
+#define DWC_SSI_CTRLR0_SPI_FRF_MASK	GENMASK(23, 22)
 
 /* Bit fields in SR, 7 bits */
 #define SR_MASK				GENMASK(6, 0)	/* cover 7 bits */
@@ -99,6 +121,8 @@ struct dw_spi_priv {
 	struct reset_ctl_bulk resets;
 	struct gpio_desc cs_gpio;	/* External chip-select gpio */
 
+	u32 (*update_cr0)(struct dw_spi_priv *priv);
+
 	void __iomem *regs;
 	unsigned long bus_clk_rate;
 	unsigned int freq;		/* Default frequency */
@@ -109,6 +133,7 @@ struct dw_spi_priv {
 	void *rx;
 	void *rx_end;
 	u32 fifo_len;			/* depth of the FIFO buffer */
+	u32 max_xfer;			/* Maximum transfer size (in bits) */
 
 	int bits_per_word;
 	int len;
@@ -127,6 +152,53 @@ static inline void dw_write(struct dw_spi_priv *priv, u32 offset, u32 val)
 	__raw_writel(val, priv->regs + offset);
 }
 
+static u32 dw_spi_dw16_update_cr0(struct dw_spi_priv *priv)
+{
+	return FIELD_PREP(CTRLR0_DFS_MASK, priv->bits_per_word - 1)
+	     | FIELD_PREP(CTRLR0_FRF_MASK, priv->type)
+	     | FIELD_PREP(CTRLR0_MODE_MASK, priv->mode)
+	     | FIELD_PREP(CTRLR0_TMOD_MASK, priv->tmode);
+}
+
+static u32 dw_spi_dw32_update_cr0(struct dw_spi_priv *priv)
+{
+	return FIELD_PREP(CTRLR0_DFS_32_MASK, priv->bits_per_word - 1)
+	     | FIELD_PREP(CTRLR0_FRF_MASK, priv->type)
+	     | FIELD_PREP(CTRLR0_MODE_MASK, priv->mode)
+	     | FIELD_PREP(CTRLR0_TMOD_MASK, priv->tmode);
+}
+
+static u32 dw_spi_dwc_update_cr0(struct dw_spi_priv *priv)
+{
+	return FIELD_PREP(DWC_SSI_CTRLR0_DFS_MASK, priv->bits_per_word - 1)
+	     | FIELD_PREP(DWC_SSI_CTRLR0_FRF_MASK, priv->type)
+	     | FIELD_PREP(DWC_SSI_CTRLR0_MODE_MASK, priv->mode)
+	     | FIELD_PREP(DWC_SSI_CTRLR0_TMOD_MASK, priv->tmode);
+}
+
+static int dw_spi_apb_init(struct udevice *bus, struct dw_spi_priv *priv)
+{
+	/* If we read zeros from DFS, then we need to use DFS_32 instead */
+	dw_write(priv, DW_SPI_SSIENR, 0);
+	dw_write(priv, DW_SPI_CTRLR0, 0xffffffff);
+	if (FIELD_GET(CTRLR0_DFS_MASK, dw_read(priv, DW_SPI_CTRLR0))) {
+		priv->max_xfer = 16;
+		priv->update_cr0 = dw_spi_dw16_update_cr0;
+	} else {
+		priv->max_xfer = 32;
+		priv->update_cr0 = dw_spi_dw32_update_cr0;
+	}
+
+	return 0;
+}
+
+static int dw_spi_dwc_init(struct udevice *bus, struct dw_spi_priv *priv)
+{
+	priv->max_xfer = 32;
+	priv->update_cr0 = dw_spi_dwc_update_cr0;
+	return 0;
+}
+
 static int request_gpio_cs(struct udevice *bus)
 {
 #if CONFIG_IS_ENABLED(DM_GPIO) && !defined(CONFIG_SPL_BUILD)
@@ -165,6 +237,10 @@ static int dw_spi_ofdata_to_platdata(struct udevice *bus)
 	/* Use 500KHz as a suitable default */
 	plat->frequency = dev_read_u32_default(bus, "spi-max-frequency",
 					       500000);
+
+	if (dev_read_bool(bus, "spi-slave"))
+		return -EINVAL;
+
 	dev_info(bus, "max-frequency=%d\n", plat->frequency);
 
 	return request_gpio_cs(bus);
@@ -259,11 +335,15 @@ static int dw_spi_reset(struct udevice *bus)
 	return 0;
 }
 
+typedef int (*dw_spi_init_t)(struct udevice *bus, struct dw_spi_priv *priv);
+
 static int dw_spi_probe(struct udevice *bus)
 {
+	dw_spi_init_t init = (dw_spi_init_t)dev_get_driver_data(bus);
 	struct dw_spi_platdata *plat = dev_get_platdata(bus);
 	struct dw_spi_priv *priv = dev_get_priv(bus);
 	int ret;
+	u32 version;
 
 	priv->regs = plat->regs;
 	priv->freq = plat->frequency;
@@ -276,6 +356,17 @@ static int dw_spi_probe(struct udevice *bus)
 	if (ret)
 		return ret;
 
+	if (!init)
+		return -EINVAL;
+	ret = init(bus, priv);
+	if (ret)
+		return ret;
+
+	version = dw_read(priv, DW_SPI_VERSION);
+	dev_dbg(bus, "ssi_version_id=%c.%c%c%c ssi_max_xfer_size=%u\n",
+		version >> 24, version >> 16, version >> 8, version,
+		priv->max_xfer);
+
 	/* Currently only bits_per_word == 8 supported */
 	priv->bits_per_word = 8;
 
@@ -320,7 +411,7 @@ static inline u32 rx_max(struct dw_spi_priv *priv)
 static void dw_writer(struct dw_spi_priv *priv)
 {
 	u32 max = tx_max(priv);
-	u16 txw = 0xFFFF;
+	u32 txw = 0xFFFFFFFF;
 
 	while (max--) {
 		/* Set the tx word if the transfer's original "tx" is not null */
@@ -406,23 +497,18 @@ static int dw_spi_xfer(struct udevice *dev, unsigned int bitlen,
 	if (flags & SPI_XFER_BEGIN)
 		external_cs_manage(dev, false);
 
-	cr0 = (priv->bits_per_word - 1) | (priv->type << SPI_FRF_OFFSET) |
-		(priv->mode << SPI_MODE_OFFSET) |
-		(priv->tmode << SPI_TMOD_OFFSET);
-
 	if (rx && tx)
-		priv->tmode = SPI_TMOD_TR;
+		priv->tmode = CTRLR0_TMOD_TR;
 	else if (rx)
-		priv->tmode = SPI_TMOD_RO;
+		priv->tmode = CTRLR0_TMOD_RO;
 	else
 		/*
-		 * In transmit only mode (SPI_TMOD_TO) input FIFO never gets
+		 * In transmit only mode (CTRL0_TMOD_TO) input FIFO never gets
 		 * any data which breaks our logic in poll_transfer() above.
 		 */
-		priv->tmode = SPI_TMOD_TR;
+		priv->tmode = CTRLR0_TMOD_TR;
 
-	cr0 &= ~SPI_TMOD_MASK;
-	cr0 |= (priv->tmode << SPI_TMOD_OFFSET);
+	cr0 = priv->update_cr0(priv);
 
 	priv->len = bitlen >> 3;
 
@@ -476,7 +562,7 @@ static int dw_spi_xfer(struct udevice *dev, unsigned int bitlen,
 
 static int dw_spi_set_speed(struct udevice *bus, uint speed)
 {
-	struct dw_spi_platdata *plat = bus->platdata;
+	struct dw_spi_platdata *plat = dev_get_platdata(bus);
 	struct dw_spi_priv *priv = dev_get_priv(bus);
 	u16 clk_div;
 
@@ -547,7 +633,35 @@ static const struct dm_spi_ops dw_spi_ops = {
 };
 
 static const struct udevice_id dw_spi_ids[] = {
-	{ .compatible = "snps,dw-apb-ssi" },
+	/* Generic compatible strings */
+
+	{ .compatible = "snps,dw-apb-ssi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "snps,dw-apb-ssi-3.20a", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "snps,dw-apb-ssi-3.22a", .data = (ulong)dw_spi_apb_init },
+	/* First version with SSI_MAX_XFER_SIZE */
+	{ .compatible = "snps,dw-apb-ssi-3.23a", .data = (ulong)dw_spi_apb_init },
+	/* First version with Dual/Quad SPI; unused by this driver */
+	{ .compatible = "snps,dw-apb-ssi-4.00a", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "snps,dw-apb-ssi-4.01", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "snps,dwc-ssi-1.01a", .data = (ulong)dw_spi_dwc_init },
+
+	/* Compatible strings for specific SoCs */
+
+	/*
+	 * Both the Cyclone V and Arria V share a device tree and have the same
+	 * version of this device. This compatible string is used for those
+	 * devices, and is not used for sofpgas in general.
+	 */
+	{ .compatible = "altr,socfpga-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "altr,socfpga-arria10-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "canaan,kendryte-k210-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "canaan,kendryte-k210-ssi", .data = (ulong)dw_spi_dwc_init },
+	{ .compatible = "intel,stratix10-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "intel,agilex-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "mscc,ocelot-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "mscc,jaguar2-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "snps,axs10x-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "snps,hsdk-spi", .data = (ulong)dw_spi_apb_init },
 	{ }
 };