[U-Boot] [PATCH v2] spi/arm-pl022: Add support for ARM PL022 spi controller

[U-Boot] [PATCH v2] spi/arm-pl022: Add support for ARM PL022 spi controller

[Vipin Kumar]

From: 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>
---
 drivers/spi/Makefile    |   1 +
 drivers/spi/pl022_spi.c | 310 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 311 insertions(+)
 create mode 100644 drivers/spi/pl022_spi.c

diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 824d357..3a4e4b0 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -42,6 +42,7 @@ 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..ba018b8
--- /dev/null
+++ b/drivers/spi/pl022_spi.c
@@ -0,0 +1,310 @@
+/*
+ * (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()
+{
+	/* 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 ((readw(pl022->ssp_pid0) == 0x22) &&
+		(readw(pl022->ssp_pid1) == 0x10) &&
+		((readw(pl022->ssp_pid2) & 0xf) == 0x04) &&
+		(readw(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 = malloc(sizeof(*ps));
+	if (!ps)
+		return NULL;
+
+	ps->slave.bus = bus;
+	ps->slave.cs = cs;
+	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;
+
+	writew(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++;
+
+	writew(cpsr, pl022->ssp_cpsr);
+	cr0 = readw(pl022->ssp_cr0);
+	writew(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_le16(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 */
+	writew(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 (readw(pl022->ssp_sr) & SSP_SR_MASK_TNF) {
+			value = (txp != NULL) ? *txp++ : 0;
+			writew(value, pl022->ssp_dr);
+			len_tx++;
+		}
+
+		if (readw(pl022->ssp_sr) & SSP_SR_MASK_RNE) {
+			value = readw(pl022->ssp_dr);
+			if (rxp)
+				*rxp++ = value;
+			len_rx++;
+		}
+	}
+
+	while (len_rx < len_tx) {
+		if (readw(pl022->ssp_sr) & SSP_SR_MASK_RNE) {
+			value = readw(pl022->ssp_dr);
+			if (rxp)
+				*rxp++ = value;
+			len_rx++;
+		}
+	}
+
+out:
+	if (flags & SPI_XFER_END)
+		spi_cs_deactivate(slave);
+
+	return ret;
+}
-- 
1.8.0

[U-Boot] [PATCH v2] spi/arm-pl022: Add support for ARM PL022 spi controller

[Stefan Roese]

On 12/12/2012 01:04 PM, Vipin Kumar wrote:
> From: 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>

I'm not that familiar with the U-Boot SPI stuff. But patch looks in
general good, so:

Acked-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan

[U-Boot] [PATCH v2] spi/arm-pl022: Add support for ARM PL022 spi controller

[Armando Visconti]

Ciao Vipin,

On 12/12/2012 01:04 PM, Vipin KUMAR wrote:
> From: 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.
>

Have you tested this patch on the new variant as well?
You should have a couple of boards there with the
new asic.

> Signed-off-by: Armando Visconti<armando.visconti@st.com>
> Signed-off-by: Vipin Kumar<vipin.kumar@st.com>
> ---
>   drivers/spi/Makefile    |   1 +
>   drivers/spi/pl022_spi.c | 310 ++++++++++++++++++++++++++++++++++++++++++++++++
>   2 files changed, 311 insertions(+)
>   create mode 100644 drivers/spi/pl022_spi.c
>
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 824d357..3a4e4b0 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -42,6 +42,7 @@ 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..ba018b8
> --- /dev/null
> +++ b/drivers/spi/pl022_spi.c
> @@ -0,0 +1,310 @@
> +/*
> + * (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 */
> +};

It's correct!
:)

> +
> +/* 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()

Maybe you can put 'void' also in the arguments.
I think we forgot it in the original patch.

> +{
> +	/* 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 ((readw(pl022->ssp_pid0) == 0x22)&&
> +		(readw(pl022->ssp_pid1) == 0x10)&&
> +		((readw(pl022->ssp_pid2)&  0xf) == 0x04)&&
> +		(readw(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 = malloc(sizeof(*ps));
> +	if (!ps)
> +		return NULL;
> +
> +	ps->slave.bus = bus;
> +	ps->slave.cs = cs;
> +	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;
> +
> +	writew(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++;
> +
> +	writew(cpsr, pl022->ssp_cpsr);
> +	cr0 = readw(pl022->ssp_cr0);
> +	writew(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_le16(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 */
> +	writew(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 (readw(pl022->ssp_sr)&  SSP_SR_MASK_TNF) {
> +			value = (txp != NULL) ? *txp++ : 0;
> +			writew(value, pl022->ssp_dr);
> +			len_tx++;
> +		}
> +
> +		if (readw(pl022->ssp_sr)&  SSP_SR_MASK_RNE) {
> +			value = readw(pl022->ssp_dr);
> +			if (rxp)
> +				*rxp++ = value;
> +			len_rx++;
> +		}
> +	}
> +
> +	while (len_rx<  len_tx) {
> +		if (readw(pl022->ssp_sr)&  SSP_SR_MASK_RNE) {
> +			value = readw(pl022->ssp_dr);
> +			if (rxp)
> +				*rxp++ = value;
> +			len_rx++;
> +		}
> +	}
> +
> +out:
> +	if (flags&  SPI_XFER_END)
> +		spi_cs_deactivate(slave);
> +
> +	return ret;
> +}

Rest is fine.
I don't know if I need to ack it, but...

Acked-by: Armando Visconti <armando.visconti@st.com>

Ciao,
Arm