[U-Boot] [PATCH v6] spi: pl022_spi: Add support for ARM PL022 spi controller

[Armando Visconti <armando.visconti@st.com>]

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

Signed-off-by: Armando Visconti <armando.visconti@st.com>
Signed-off-by: Vipin Kumar <vipin.kumar@st.com>
Acked-by: Stefan Roese <sr@denx.de>
---
v5->v6

 1. Make use of spi_alloc_slave() macro.
 2. Changed the identation on 'if statement' as requested
    by Jagan.

 drivers/spi/Makefile    |   1 +
 drivers/spi/pl022_spi.c | 308 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 309 insertions(+)
 create mode 100644 drivers/spi/pl022_spi.c

diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index d08609e..b6443b1 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -47,6 +47,7 @@ COBJS-$(CONFIG_MXC_SPI) += mxc_spi.o
 COBJS-$(CONFIG_MXS_SPI) += mxs_spi.o
 COBJS-$(CONFIG_OC_TINY_SPI) += oc_tiny_spi.o
 COBJS-$(CONFIG_OMAP3_SPI) += omap3_spi.o
+COBJS-$(CONFIG_PL022_SPI) += pl022_spi.o
 COBJS-$(CONFIG_SOFT_SPI) += soft_spi.o
 COBJS-$(CONFIG_SH_SPI) += sh_spi.o
 COBJS-$(CONFIG_FSL_ESPI) += fsl_espi.o
diff --git a/drivers/spi/pl022_spi.c b/drivers/spi/pl022_spi.c
new file mode 100644
index 0000000..5b47413
--- /dev/null
+++ b/drivers/spi/pl022_spi.c
@@ -0,0 +1,308 @@
+/*
+ * (C) Copyright 2012
+ * Armando Visconti, ST Microelectronics, armando.visconti at st.com.
+ *
+ * Driver for ARM PL022 SPI Controller. Based on atmel_spi.c
+ * by Atmel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <malloc.h>
+#include <spi.h>
+#include <asm/io.h>
+#include <asm/arch/hardware.h>
+
+/* SSP registers mapping */
+struct pl022 {
+	u32	ssp_cr0;	/* 0x000 */
+	u32	ssp_cr1;	/* 0x004 */
+	u32	ssp_dr;		/* 0x008 */
+	u32	ssp_sr;		/* 0x00c */
+	u32	ssp_cpsr;	/* 0x010 */
+	u32	ssp_imsc;	/* 0x014 */
+	u32	ssp_ris;	/* 0x018 */
+	u32	ssp_mis;	/* 0x01c */
+	u32	ssp_icr;	/* 0x020 */
+	u32	ssp_dmacr;	/* 0x024 */
+	u8	reserved_1[0x080 - 0x028];
+	u32	ssp_itcr;	/* 0x080 */
+	u32	ssp_itip;	/* 0x084 */
+	u32	ssp_itop;	/* 0x088 */
+	u32	ssp_tdr;	/* 0x08c */
+	u8	reserved_2[0xFE0 - 0x090];
+	u32	ssp_pid0;	/* 0xfe0 */
+	u32	ssp_pid1;	/* 0xfe4 */
+	u32	ssp_pid2;	/* 0xfe8 */
+	u32	ssp_pid3;	/* 0xfec */
+	u32	ssp_cid0;	/* 0xff0 */
+	u32	ssp_cid1;	/* 0xff4 */
+	u32	ssp_cid2;	/* 0xff8 */
+	u32	ssp_cid3;	/* 0xffc */
+};
+
+/* SSP Control Register 0  - SSP_CR0 */
+#define SSP_CR0_SPO		(0x1 << 6)
+#define SSP_CR0_SPH		(0x1 << 7)
+#define SSP_CR0_8BIT_MODE	(0x07)
+#define SSP_SCR_MAX		(0xFF)
+#define SSP_SCR_SHFT		8
+
+/* SSP Control Register 0  - SSP_CR1 */
+#define SSP_CR1_MASK_SSE	(0x1 << 1)
+
+#define SSP_CPSR_MAX		(0xFE)
+
+/* 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 {
+	struct spi_slave slave;
+	void *regs;
+	unsigned int freq;
+};
+
+static inline struct pl022_spi_slave *to_pl022_spi(struct spi_slave *slave)
+{
+	return container_of(slave, struct pl022_spi_slave, slave);
+}
+
+/*
+ * Following three functions should be provided by the
+ * board support package.
+ */
+int __weak spi_cs_is_valid(unsigned int bus, unsigned int cs)
+{
+	return 1;
+}
+
+void __weak spi_cs_activate(struct spi_slave *slave)
+{
+	/* do nothing */
+}
+
+void __weak spi_cs_deactivate(struct spi_slave *slave)
+{
+	/* do nothing */
+}
+
+void spi_init(void)
+{
+	/* do nothing */
+}
+
+/*
+ * 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)
+{
+	struct pl022 *pl022 = (struct pl022 *)ps->regs;
+
+	/* PL022 version is 0x00041022 */
+	if ((readl(&pl022->ssp_pid0) == 0x22) &&
+			(readl(&pl022->ssp_pid1) == 0x10) &&
+			((readl(&pl022->ssp_pid2) & 0xf) == 0x04) &&
+			(readl(&pl022->ssp_pid3) == 0x00))
+		return 1;
+
+	return 0;
+}
+
+struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
+			unsigned int max_hz, unsigned int mode)
+{
+	struct pl022_spi_slave *ps;
+	struct pl022 *pl022;
+	u16 scr = 1, prescaler, cr0 = 0, cpsr = 0;
+
+	if (!spi_cs_is_valid(bus, cs))
+		return NULL;
+
+	ps = spi_alloc_slave(struct pl022_spi_slave, bus, cs);
+	if (!ps)
+		return NULL;
+
+	ps->freq = max_hz;
+
+	switch (bus) {
+	case 0:
+		ps->regs = (void *)CONFIG_SYS_SPI_BASE;
+		break;
+#ifdef CONFIG_SYS_SPI_BASE1
+	case 1:
+		ps->regs = (void *)CONFIG_SYS_SPI_BASE1;
+		break;
+#endif
+#ifdef CONFIG_SYS_SPI_BASE2
+	case 2:
+		ps->regs = (void *)CONFIG_SYS_SPI_BASE2;
+		break;
+#endif
+#ifdef CONFIG_SYS_SPI_BASE3
+	case 3:
+		ps->regs = (void *)CONFIG_SYS_SPI_BASE3;
+		break;
+#endif
+	default:
+		free(ps);
+		return NULL;
+	}
+
+	pl022 = (struct pl022 *)ps->regs;
+
+	/* Check the PL022 version */
+	if (!pl022_is_supported(ps)) {
+		free(ps);
+		return NULL;
+	}
+
+	/* Set requested polarity and 8bit mode */
+	cr0 = SSP_CR0_8BIT_MODE;
+	cr0 |= (mode & SPI_CPHA) ? SSP_CR0_SPH : 0;
+	cr0 |= (mode & SPI_CPOL) ? SSP_CR0_SPO : 0;
+
+	writel(cr0, &pl022->ssp_cr0);
+
+	/* Program the SSPClk frequency */
+	prescaler = CONFIG_SYS_SPI_CLK / ps->freq;
+
+	if (prescaler <= 0xFF) {
+		cpsr = prescaler;
+	} else {
+		for (scr = 1; scr <= SSP_SCR_MAX; scr++) {
+			if (!(prescaler % scr)) {
+				cpsr = prescaler / scr;
+				if (cpsr <= SSP_CPSR_MAX)
+					break;
+			}
+		}
+
+		if (scr > SSP_SCR_MAX) {
+			scr = SSP_SCR_MAX;
+			cpsr = prescaler / scr;
+			cpsr &= SSP_CPSR_MAX;
+		}
+	}
+
+	if (cpsr & 0x1)
+		cpsr++;
+
+	writel(cpsr, &pl022->ssp_cpsr);
+	cr0 = readl(&pl022->ssp_cr0);
+	writel(cr0 | (scr - 1) << SSP_SCR_SHFT, &pl022->ssp_cr0);
+
+	return &ps->slave;
+}
+
+void spi_free_slave(struct spi_slave *slave)
+{
+	struct pl022_spi_slave *ps = to_pl022_spi(slave);
+
+	free(ps);
+}
+
+int spi_claim_bus(struct spi_slave *slave)
+{
+	struct pl022_spi_slave *ps = to_pl022_spi(slave);
+	struct pl022 *pl022 = (struct pl022 *)ps->regs;
+
+	/* Enable the SPI hardware */
+	setbits_le32(&pl022->ssp_cr1, SSP_CR1_MASK_SSE);
+
+	return 0;
+}
+
+void spi_release_bus(struct spi_slave *slave)
+{
+	struct pl022_spi_slave *ps = to_pl022_spi(slave);
+	struct pl022 *pl022 = (struct pl022 *)ps->regs;
+
+	/* Disable the SPI hardware */
+	writel(0x0, &pl022->ssp_cr1);
+}
+
+int spi_xfer(struct spi_slave *slave, unsigned int bitlen,
+		const void *dout, void *din, unsigned long flags)
+{
+	struct pl022_spi_slave *ps = to_pl022_spi(slave);
+	struct pl022 *pl022 = (struct pl022 *)ps->regs;
+	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 */
+		goto out;
+
+	/*
+	 * 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) {
+		ret = -1;
+
+		/* Errors always terminate an ongoing transfer */
+		flags |= SPI_XFER_END;
+		goto out;
+	}
+
+	len = bitlen / 8;
+
+	if (flags & SPI_XFER_BEGIN)
+		spi_cs_activate(slave);
+
+	while (len_tx < len) {
+		if (readl(&pl022->ssp_sr) & SSP_SR_MASK_TNF) {
+			value = (txp != NULL) ? *txp++ : 0;
+			writel(value, &pl022->ssp_dr);
+			len_tx++;
+		}
+
+		if (readl(&pl022->ssp_sr) & SSP_SR_MASK_RNE) {
+			value = readl(&pl022->ssp_dr);
+			if (rxp)
+				*rxp++ = value;
+			len_rx++;
+		}
+	}
+
+	while (len_rx < len_tx) {
+		if (readl(&pl022->ssp_sr) & SSP_SR_MASK_RNE) {
+			value = readl(&pl022->ssp_dr);
+			if (rxp)
+				*rxp++ = value;
+			len_rx++;
+		}
+	}
+
+out:
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(slave);
+
+	return ret;
+}
-- 
1.7.11.7