spi: add support for ARM PL022 SPI controller

This adds support for the ARM PL022 SPI controller for the standard
variant (0x00041022) which has a 16bit wide and 8 locations deep TX/RX
FIFO.

A few parts were borrowed from the Linux kernel driver.

Cc: Armando Visconti <armando.visconti@st.com>
Cc: Vipin Kumar <vipin.kumar@st.com>
Signed-off-by: Quentin Schulz <quentin.schulz@bootlin.com>

drivers/spi/Kconfig

@@ -125,6 +125,14 @@ config PIC32_SPI
 	  to access the SPI NOR flash, MMC-over-SPI on platforms based on
 	  Microchip PIC32 family devices.
 
+config PL022_SPI
+	bool "ARM AMBA PL022 SSP controller driver"
+	depends on ARM
+	help
+	  This selects the ARM(R) AMBA(R) PrimeCell PL022 SSP
+	  controller. If you have an embedded system with an AMBA(R)
+	  bus and a PL022 controller, say Y or M here.
+
 config RENESAS_RPC_SPI
 	bool "Renesas RPC SPI driver"
 	depends on RCAR_GEN3

drivers/spi/Makefile

@@ -38,6 +38,7 @@ obj-$(CONFIG_MXS_SPI) += mxs_spi.o
 obj-$(CONFIG_ATCSPI200_SPI) += atcspi200_spi.o
 obj-$(CONFIG_OMAP3_SPI) += omap3_spi.o
 obj-$(CONFIG_PIC32_SPI) += pic32_spi.o
+obj-$(CONFIG_PL022_SPI) += pl022_spi.o
 obj-$(CONFIG_RENESAS_RPC_SPI) += renesas_rpc_spi.o
 obj-$(CONFIG_ROCKCHIP_SPI) += rk_spi.o
 obj-$(CONFIG_SANDBOX_SPI) += sandbox_spi.o

drivers/spi/pl022_spi.c

@@ -0,0 +1,338 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2012
+ * Armando Visconti, ST Microelectronics, armando.visconti@st.com.
+ *
+ * (C) Copyright 2018
+ * Quentin Schulz, Bootlin, quentin.schulz@bootlin.com
+ *
+ * Driver for ARM PL022 SPI Controller.
+ */
+
+#include <asm/io.h>
+#include <clk.h>
+#include <common.h>
+#include <dm.h>
+#include <dm/platform_data/pl022_spi.h>
+#include <fdtdec.h>
+#include <linux/bitops.h>
+#include <linux/bug.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <spi.h>
+
+#define SSP_CR0		0x000
+#define SSP_CR1		0x004
+#define SSP_DR		0x008
+#define SSP_SR		0x00C
+#define SSP_CPSR	0x010
+#define SSP_IMSC	0x014
+#define SSP_RIS		0x018
+#define SSP_MIS		0x01C
+#define SSP_ICR		0x020
+#define SSP_DMACR	0x024
+#define SSP_CSR		0x030 /* vendor extension */
+#define SSP_ITCR	0x080
+#define SSP_ITIP	0x084
+#define SSP_ITOP	0x088
+#define SSP_TDR		0x08C
+
+#define SSP_PID0	0xFE0
+#define SSP_PID1	0xFE4
+#define SSP_PID2	0xFE8
+#define SSP_PID3	0xFEC
+
+#define SSP_CID0	0xFF0
+#define SSP_CID1	0xFF4
+#define SSP_CID2	0xFF8
+#define SSP_CID3	0xFFC
+
+/* SSP Control Register 0  - SSP_CR0 */
+#define SSP_CR0_SPO		(0x1 << 6)
+#define SSP_CR0_SPH		(0x1 << 7)
+#define SSP_CR0_BIT_MODE(x)	((x) - 1)
+#define SSP_SCR_MIN		(0x00)
+#define SSP_SCR_MAX		(0xFF)
+#define SSP_SCR_SHFT		8
+#define DFLT_CLKRATE		2
+
+/* SSP Control Register 1  - SSP_CR1 */
+#define SSP_CR1_MASK_SSE	(0x1 << 1)
+
+#define SSP_CPSR_MIN		(0x02)
+#define SSP_CPSR_MAX		(0xFE)
+#define DFLT_PRESCALE		(0x40)
+
+/* SSP Status Register - SSP_SR */
+#define SSP_SR_MASK_TFE		(0x1 << 0) /* Transmit FIFO empty */
+#define SSP_SR_MASK_TNF		(0x1 << 1) /* Transmit FIFO not full */
+#define SSP_SR_MASK_RNE		(0x1 << 2) /* Receive FIFO not empty */
+#define SSP_SR_MASK_RFF		(0x1 << 3) /* Receive FIFO full */
+#define SSP_SR_MASK_BSY		(0x1 << 4) /* Busy Flag */
+
+struct pl022_spi_slave {
+	void *base;
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	struct clk clk;
+#else
+	unsigned int freq;
+#endif
+};
+
+/*
+ * ARM PL022 exists in different 'flavors'.
+ * This drivers currently support the standard variant (0x00041022), that has a
+ * 16bit wide and 8 locations deep TX/RX FIFO.
+ */
+static int pl022_is_supported(struct pl022_spi_slave *ps)
+{
+	/* PL022 version is 0x00041022 */
+	if ((readw(ps->base + SSP_PID0) == 0x22) &&
+	    (readw(ps->base + SSP_PID1) == 0x10) &&
+	    ((readw(ps->base + SSP_PID2) & 0xf) == 0x04) &&
+	    (readw(ps->base + SSP_PID3) == 0x00))
+		return 1;
+
+	return 0;
+}
+
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+static int pl022_spi_ofdata_to_platdata(struct udevice *bus)
+{
+	struct pl022_spi_pdata *plat = bus->platdata;
+	const void *fdt = gd->fdt_blob;
+	int node = dev_of_offset(bus);
+
+	plat->addr = fdtdec_get_addr_size(fdt, node, "reg", &plat->size);
+
+	return clk_get_by_index(bus, 0, &plat->clk);
+}
+#endif
+
+static int pl022_spi_probe(struct udevice *bus)
+{
+	struct pl022_spi_pdata *plat = dev_get_platdata(bus);
+	struct pl022_spi_slave *ps = dev_get_priv(bus);
+
+	ps->base = ioremap(plat->addr, plat->size);
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	ps->clk = plat->clk;
+#else
+	ps->freq = plat->freq;
+#endif
+
+	/* Check the PL022 version */
+	if (!pl022_is_supported(ps))
+		return -ENOTSUPP;
+
+	/* 8 bits per word, high polarity and default clock rate */
+	writew(SSP_CR0_BIT_MODE(8), ps->base + SSP_CR0);
+	writew(DFLT_PRESCALE, ps->base + SSP_CPSR);
+
+	return 0;
+}
+
+static void flush(struct pl022_spi_slave *ps)
+{
+	do {
+		while (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE)
+			readw(ps->base + SSP_DR);
+	} while (readw(ps->base + SSP_SR) & SSP_SR_MASK_BSY);
+}
+
+static int pl022_spi_claim_bus(struct udevice *dev)
+{
+	struct udevice *bus = dev->parent;
+	struct pl022_spi_slave *ps = dev_get_priv(bus);
+	u16 reg;
+
+	/* Enable the SPI hardware */
+	reg = readw(ps->base + SSP_CR1);
+	reg |= SSP_CR1_MASK_SSE;
+	writew(reg, ps->base + SSP_CR1);
+
+	flush(ps);
+
+	return 0;
+}
+
+static int pl022_spi_release_bus(struct udevice *dev)
+{
+	struct udevice *bus = dev->parent;
+	struct pl022_spi_slave *ps = dev_get_priv(bus);
+	u16 reg;
+
+	flush(ps);
+
+	/* Disable the SPI hardware */
+	reg = readw(ps->base + SSP_CR1);
+	reg &= ~SSP_CR1_MASK_SSE;
+	writew(reg, ps->base + SSP_CR1);
+
+	return 0;
+}
+
+static int pl022_spi_xfer(struct udevice *dev, unsigned int bitlen,
+			  const void *dout, void *din, unsigned long flags)
+{
+	struct udevice *bus = dev->parent;
+	struct pl022_spi_slave *ps = dev_get_priv(bus);
+	u32		len_tx = 0, len_rx = 0, len;
+	u32		ret = 0;
+	const u8	*txp = dout;
+	u8		*rxp = din, value;
+
+	if (bitlen == 0)
+		/* Finish any previously submitted transfers */
+		return 0;
+
+	/*
+	 * TODO: The controller can do non-multiple-of-8 bit
+	 * transfers, but this driver currently doesn't support it.
+	 *
+	 * It's also not clear how such transfers are supposed to be
+	 * represented as a stream of bytes...this is a limitation of
+	 * the current SPI interface.
+	 */
+	if (bitlen % 8) {
+		/* Errors always terminate an ongoing transfer */
+		flags |= SPI_XFER_END;
+		return -1;
+	}
+
+	len = bitlen / 8;
+
+	while (len_tx < len) {
+		if (readw(ps->base + SSP_SR) & SSP_SR_MASK_TNF) {
+			value = txp ? *txp++ : 0;
+			writew(value, ps->base + SSP_DR);
+			len_tx++;
+		}
+
+		if (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE) {
+			value = readw(ps->base + SSP_DR);
+			if (rxp)
+				*rxp++ = value;
+			len_rx++;
+		}
+	}
+
+	while (len_rx < len_tx) {
+		if (readw(ps->base + SSP_SR) & SSP_SR_MASK_RNE) {
+			value = readw(ps->base + SSP_DR);
+			if (rxp)
+				*rxp++ = value;
+			len_rx++;
+		}
+	}
+
+	return ret;
+}
+
+static inline u32 spi_rate(u32 rate, u16 cpsdvsr, u16 scr)
+{
+	return rate / (cpsdvsr * (1 + scr));
+}
+
+static int pl022_spi_set_speed(struct udevice *bus, uint speed)
+{
+	struct pl022_spi_slave *ps = dev_get_priv(bus);
+	u16 scr = SSP_SCR_MIN, cr0 = 0, cpsr = SSP_CPSR_MIN, best_scr = scr,
+	    best_cpsr = cpsr;
+	u32 min, max, best_freq = 0, tmp;
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	u32 rate = clk_get_rate(&ps->clk);
+#else
+	u32 rate = ps->freq;
+#endif
+	bool found = false;
+
+	max = spi_rate(rate, SSP_CPSR_MIN, SSP_SCR_MIN);
+	min = spi_rate(rate, SSP_CPSR_MAX, SSP_SCR_MAX);
+
+	if (speed > max || speed < min) {
+		pr_err("Tried to set speed to %dHz but min=%d and max=%d\n",
+		       speed, min, max);
+		return -EINVAL;
+	}
+
+	while (cpsr <= SSP_CPSR_MAX && !found) {
+		while (scr <= SSP_SCR_MAX) {
+			tmp = spi_rate(rate, cpsr, scr);
+
+			if (abs(speed - tmp) < abs(speed - best_freq)) {
+				best_freq = tmp;
+				best_cpsr = cpsr;
+				best_scr = scr;
+
+				if (tmp == speed) {
+					found = true;
+					break;
+				}
+			}
+
+			scr++;
+		}
+		cpsr += 2;
+		scr = SSP_SCR_MIN;
+	}
+
+	writew(best_cpsr, ps->base + SSP_CPSR);
+	cr0 = readw(ps->base + SSP_CR0);
+	writew(cr0 | (best_scr << SSP_SCR_SHFT), ps->base + SSP_CR0);
+
+	return 0;
+}
+
+static int pl022_spi_set_mode(struct udevice *bus, uint mode)
+{
+	struct pl022_spi_slave *ps = dev_get_priv(bus);
+	u16 reg;
+
+	reg = readw(ps->base + SSP_CR0);
+	reg &= ~(SSP_CR0_SPH | SSP_CR0_SPO);
+	if (mode & SPI_CPHA)
+		reg |= SSP_CR0_SPH;
+	if (mode & SPI_CPOL)
+		reg |= SSP_CR0_SPO;
+	writew(reg, ps->base + SSP_CR0);
+
+	return 0;
+}
+
+static int pl022_cs_info(struct udevice *bus, uint cs,
+			 struct spi_cs_info *info)
+{
+	return 0;
+}
+
+static const struct dm_spi_ops pl022_spi_ops = {
+	.claim_bus      = pl022_spi_claim_bus,
+	.release_bus    = pl022_spi_release_bus,
+	.xfer           = pl022_spi_xfer,
+	.set_speed      = pl022_spi_set_speed,
+	.set_mode       = pl022_spi_set_mode,
+	.cs_info        = pl022_cs_info,
+};
+
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+static const struct udevice_id pl022_spi_ids[] = {
+	{ .compatible = "arm,pl022-spi" },
+	{ }
+};
+#endif
+
+U_BOOT_DRIVER(pl022_spi) = {
+	.name   = "pl022_spi",
+	.id     = UCLASS_SPI,
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	.of_match = pl022_spi_ids,
+#endif
+	.ops    = &pl022_spi_ops,
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	.ofdata_to_platdata = pl022_spi_ofdata_to_platdata,
+#endif
+	.platdata_auto_alloc_size = sizeof(struct pl022_spi_pdata),
+	.priv_auto_alloc_size = sizeof(struct pl022_spi_slave),
+	.probe  = pl022_spi_probe,
+};

include/dm/platform_data/pl022_spi.h

@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * (C) Copyright 2018
+ * Quentin Schulz, Bootlin, quentin.schulz@bootlin.com
+ *
+ * Structure for use with U_BOOT_DEVICE for pl022 SPI devices or to use
+ * in ofdata_to_platdata.
+ */
+
+#ifndef __PL022_SPI_H__
+#define __PL022_SPI_H__
+
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+#include <clk.h>
+#endif
+#include <fdtdec.h>
+
+struct pl022_spi_pdata {
+	fdt_addr_t addr;
+	fdt_size_t size;
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	struct clk clk;
+#else
+	unsigned int freq;
+#endif
+};
+
+#endif