[PATCH v3 0/2] Xilinx Slave Serial FPGA Manager

[PATCH v3 0/2] Xilinx Slave Serial FPGA Manager

[Anatolij Gustschin]

This series adds an FPGA manager driver for Xilinx Spartan6 FPGAs
that can configure them using an SPI port and two GPIOs.

Anatolij Gustschin (2):
  dt: bindings: fpga: add xilinx slave-serial binding description
  fpga manager: Add Xilinx slave serial SPI driver

Changes in v3:

 - extend example to show the usage in SPI master node, connected
   to the fpga-region node
 - use named constant for udelay()/usleep_range() arguments
 - drop not needed .owner init
 - correct module licence (GPL v2)
 - fix build warning with newer gcc (in min() macro)

Changes in v2:

 - corrected gpios properties and node name in example
   in DT binding document
 - rebased on v4.10

 .../bindings/fpga/xilinx-slave-serial.txt          |  24 +++
 drivers/fpga/Kconfig                               |   7 +
 drivers/fpga/Makefile                              |   1 +
 drivers/fpga/xilinx-spi.c                          | 181 +++++++++++++++++++++
 4 files changed, 213 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/fpga/xilinx-slave-serial.txt
 create mode 100644 drivers/fpga/xilinx-spi.c

-- 
2.7.4

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[PATCH v3 1/2] dt: bindings: fpga: add xilinx slave-serial binding description

[Anatolij Gustschin]

Add dt binding documentation details for Xilinx FPGA configuration
over slave serial interface.

Signed-off-by: Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>
---
Changes in v3:

 - extend example to show the usage in SPI master node, connected
   to the fpga-region node

Changes in v2:

 - correct gpios properties in example to match above description

 - use fpga-mgr@0 instead of fpga-spi@0 in example

 .../bindings/fpga/xilinx-slave-serial.txt          | 44 ++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/fpga/xilinx-slave-serial.txt

diff --git a/Documentation/devicetree/bindings/fpga/xilinx-slave-serial.txt b/Documentation/devicetree/bindings/fpga/xilinx-slave-serial.txt
new file mode 100644
index 0000000..9766f74
--- /dev/null
+++ b/Documentation/devicetree/bindings/fpga/xilinx-slave-serial.txt
@@ -0,0 +1,44 @@
+Xilinx Slave Serial SPI FPGA Manager
+
+Xilinx Spartan-6 FPGAs support a method of loading the bitstream over
+what is referred to as "slave serial" interface.
+The slave serial link is not technically SPI, and might require extra
+circuits in order to play nicely with other SPI slaves on the same bus.
+
+See https://www.xilinx.com/support/documentation/user_guides/ug380.pdf
+
+Required properties:
+- compatible: should contain "xlnx,fpga-slave-serial"
+- reg: spi chip select of the FPGA
+- prog_b-gpios: config pin (referred to as PROGRAM_B in the manual)
+- done-gpios: config status pin (referred to as DONE in the manual)
+
+Example for full FPGA configuration:
+
+	fpga-region0 {
+		compatible = "fpga-region";
+		fpga-mgr = <&fpga_mgr_spi>;
+		#address-cells = <0x1>;
+		#size-cells = <0x1>;
+	};
+
+	spi1: spi@10680 {
+		compatible = "marvell,armada-xp-spi", "marvell,orion-spi";
+		pinctrl-0 = <&spi0_pins>;
+		pinctrl-names = "default";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		cell-index = <1>;
+		interrupts = <92>;
+		clocks = <&coreclk 0>;
+		status = "okay";
+
+		fpga_mgr_spi: fpga-mgr@0 {
+			compatible = "xlnx,fpga-slave-serial";
+			spi-max-frequency = <60000000>;
+			spi-cpha;
+			reg = <0>;
+			done-gpios = <&gpio0 9 GPIO_ACTIVE_HIGH>;
+			prog_b-gpios = <&gpio0 29 GPIO_ACTIVE_LOW>;
+		};
+	};
-- 
2.7.4

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[PATCH v3 2/2] fpga manager: Add Xilinx slave serial SPI driver

[Anatolij Gustschin]

The driver loads FPGA firmware over SPI, using the "slave serial"
configuration interface on Xilinx FPGAs.

Signed-off-by: Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>
---
This patch requires patch https://lkml.org/lkml/2017/2/15/667
for building

Changes in v3:

 - use named constant for udelay()/usleep_range() arguments
 - drop not needed .owner init
 - correct module licence (GPL v2)
 - fix build warning with newer gcc (in min() macro)

Changes in v2:

 - rebased on v4.10

 drivers/fpga/Kconfig      |   7 ++
 drivers/fpga/Makefile     |   1 +
 drivers/fpga/xilinx-spi.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 193 insertions(+)
 create mode 100644 drivers/fpga/xilinx-spi.c

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index ce861a2..6b42786 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -33,6 +33,13 @@ config FPGA_MGR_SOCFPGA_A10
 	help
 	  FPGA manager driver support for Altera Arria10 SoCFPGA.
 
+config FPGA_MGR_XILINX_SPI
+	tristate "Xilinx Configuration over Slave Serial (SPI)"
+	depends on SPI
+	help
+	  FPGA manager driver support for Xilinx FPGA configuration
+	  over slave serial interface.
+
 config FPGA_MGR_ZYNQ_FPGA
 	tristate "Xilinx Zynq FPGA"
 	depends on ARCH_ZYNQ || COMPILE_TEST
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index 8df07bc..7582c5a 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_FPGA)			+= fpga-mgr.o
 # FPGA Manager Drivers
 obj-$(CONFIG_FPGA_MGR_SOCFPGA)		+= socfpga.o
 obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10)	+= socfpga-a10.o
+obj-$(CONFIG_FPGA_MGR_XILINX_SPI)	+= xilinx-spi.o
 obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
 
 # FPGA Bridge Drivers
diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
new file mode 100644
index 0000000..af95727
--- /dev/null
+++ b/drivers/fpga/xilinx-spi.c
@@ -0,0 +1,185 @@
+/*
+ * Xilinx Spartan6 Slave Serial SPI Driver
+ *
+ * Copyright (C) 2017 DENX Software Engineering
+ *
+ * Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * Manage Xilinx FPGA firmware that is loaded over SPI using
+ * the slave serial configuration interface.
+ */
+
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/fpga/fpga-mgr.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/of.h>
+#include <linux/spi/spi.h>
+#include <linux/sizes.h>
+
+#define FPGA_MIN_CFG_WAIT_US	10
+
+struct xilinx_spi_conf {
+	struct spi_device *spi;
+	struct gpio_desc *prog_b;
+	struct gpio_desc *done;
+};
+
+static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
+{
+	struct xilinx_spi_conf *conf = mgr->priv;
+
+	if (!gpiod_get_value(conf->done))
+		return FPGA_MGR_STATE_RESET;
+
+	return FPGA_MGR_STATE_UNKNOWN;
+}
+
+static int xilinx_spi_write_init(struct fpga_manager *mgr,
+				 struct fpga_image_info *info,
+				 const char *buf, size_t count)
+{
+	struct xilinx_spi_conf *conf = mgr->priv;
+	const size_t prog_latency_1000us = 1000;
+	const size_t prog_pulse_1us = 1;
+
+	if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
+		dev_err(&mgr->dev, "Partial reconfiguration not supported.\n");
+		return -EINVAL;
+	}
+
+	gpiod_set_value(conf->prog_b, 1);
+
+	udelay(prog_pulse_1us); /* min is 500 ns */
+
+	gpiod_set_value(conf->prog_b, 0);
+
+	if (gpiod_get_value(conf->done)) {
+		dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
+		return -EIO;
+	}
+
+	/* program latency */
+	usleep_range(prog_latency_1000us, prog_latency_1000us + 500);
+	return 0;
+}
+
+static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
+			    size_t count)
+{
+	struct xilinx_spi_conf *conf = mgr->priv;
+	const char *fw_data = buf;
+	const char *fw_data_end = fw_data + count;
+
+	while (fw_data < fw_data_end) {
+		size_t remaining, stride;
+		int ret;
+
+		remaining = fw_data_end - fw_data;
+		stride = min_t(size_t, remaining, SZ_4K);
+
+		ret = spi_write(conf->spi, fw_data, stride);
+		if (ret) {
+			dev_err(&mgr->dev, "SPI error in firmware write: %d\n",
+				ret);
+			return ret;
+		}
+		fw_data += stride;
+	}
+
+	return 0;
+}
+
+static int xilinx_spi_write_complete(struct fpga_manager *mgr,
+				     struct fpga_image_info *info)
+{
+	struct xilinx_spi_conf *conf = mgr->priv;
+	int wait;
+
+	if (gpiod_get_value(conf->done))
+		return 0;
+
+	wait = info->config_complete_timeout_us / FPGA_MIN_CFG_WAIT_US;
+	if (info->config_complete_timeout_us % FPGA_MIN_CFG_WAIT_US)
+		wait += 1;
+
+	while (wait--) {
+		usleep_range(FPGA_MIN_CFG_WAIT_US, FPGA_MIN_CFG_WAIT_US + 5);
+
+		if (gpiod_get_value(conf->done))
+			return 0;
+	}
+
+	dev_err(&mgr->dev, "Timeout after config data transfer.\n");
+	return -ETIMEDOUT;
+}
+
+static const struct fpga_manager_ops xilinx_spi_ops = {
+	.state = xilinx_spi_state,
+	.write_init = xilinx_spi_write_init,
+	.write = xilinx_spi_write,
+	.write_complete = xilinx_spi_write_complete,
+};
+
+static int xilinx_spi_probe(struct spi_device *spi)
+{
+	struct xilinx_spi_conf *conf;
+
+	conf = devm_kzalloc(&spi->dev, sizeof(*conf), GFP_KERNEL);
+	if (!conf)
+		return -ENOMEM;
+
+	conf->spi = spi;
+
+	/* PROGRAM_B is active low */
+	conf->prog_b = devm_gpiod_get(&spi->dev, "prog_b", GPIOD_OUT_LOW);
+	if (IS_ERR(conf->prog_b)) {
+		dev_err(&spi->dev, "Failed to get PROGRAM_B gpio: %ld\n",
+			PTR_ERR(conf->prog_b));
+		return PTR_ERR(conf->prog_b);
+	}
+
+	conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
+	if (IS_ERR(conf->done)) {
+		dev_err(&spi->dev, "Failed to get DONE gpio: %ld\n",
+			PTR_ERR(conf->done));
+		return PTR_ERR(conf->done);
+	}
+
+	return fpga_mgr_register(&spi->dev, "Xilinx Slave Serial FPGA Manager",
+				 &xilinx_spi_ops, conf);
+}
+
+static int xilinx_spi_remove(struct spi_device *spi)
+{
+	fpga_mgr_unregister(&spi->dev);
+
+	return 0;
+}
+
+static const struct of_device_id xlnx_spi_of_match[] = {
+	{ .compatible = "xlnx,fpga-slave-serial", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, xlnx_spi_of_match);
+
+static struct spi_driver xilinx_slave_spi_driver = {
+	.driver = {
+		.name = "xlnx-slave-spi",
+		.of_match_table = of_match_ptr(xlnx_spi_of_match),
+	},
+	.probe = xilinx_spi_probe,
+	.remove = xilinx_spi_remove,
+};
+
+module_spi_driver(xilinx_slave_spi_driver)
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>");
+MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SPI");
-- 
2.7.4

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Re: [PATCH v3 2/2] fpga manager: Add Xilinx slave serial SPI driver

[Michal Simek]

On 22.2.2017 11:39, Anatolij Gustschin wrote:
> The driver loads FPGA firmware over SPI, using the "slave serial"
> configuration interface on Xilinx FPGAs.
> 
> Signed-off-by: Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>
> ---
> This patch requires patch https://lkml.org/lkml/2017/2/15/667
> for building
> 
> Changes in v3:
> 
>  - use named constant for udelay()/usleep_range() arguments
>  - drop not needed .owner init
>  - correct module licence (GPL v2)
>  - fix build warning with newer gcc (in min() macro)
> 
> Changes in v2:
> 
>  - rebased on v4.10
> 
>  drivers/fpga/Kconfig      |   7 ++
>  drivers/fpga/Makefile     |   1 +
>  drivers/fpga/xilinx-spi.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 193 insertions(+)
>  create mode 100644 drivers/fpga/xilinx-spi.c
> 
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index ce861a2..6b42786 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -33,6 +33,13 @@ config FPGA_MGR_SOCFPGA_A10
>  	help
>  	  FPGA manager driver support for Altera Arria10 SoCFPGA.
>  
> +config FPGA_MGR_XILINX_SPI
> +	tristate "Xilinx Configuration over Slave Serial (SPI)"
> +	depends on SPI
> +	help
> +	  FPGA manager driver support for Xilinx FPGA configuration
> +	  over slave serial interface.
> +
>  config FPGA_MGR_ZYNQ_FPGA
>  	tristate "Xilinx Zynq FPGA"
>  	depends on ARCH_ZYNQ || COMPILE_TEST
> diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> index 8df07bc..7582c5a 100644
> --- a/drivers/fpga/Makefile
> +++ b/drivers/fpga/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_FPGA)			+= fpga-mgr.o
>  # FPGA Manager Drivers
>  obj-$(CONFIG_FPGA_MGR_SOCFPGA)		+= socfpga.o
>  obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10)	+= socfpga-a10.o
> +obj-$(CONFIG_FPGA_MGR_XILINX_SPI)	+= xilinx-spi.o
>  obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
>  
>  # FPGA Bridge Drivers
> diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
> new file mode 100644
> index 0000000..af95727
> --- /dev/null
> +++ b/drivers/fpga/xilinx-spi.c
> @@ -0,0 +1,185 @@
> +/*
> + * Xilinx Spartan6 Slave Serial SPI Driver
> + *
> + * Copyright (C) 2017 DENX Software Engineering
> + *
> + * Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * Manage Xilinx FPGA firmware that is loaded over SPI using
> + * the slave serial configuration interface.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/fpga/fpga-mgr.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/of.h>
> +#include <linux/spi/spi.h>
> +#include <linux/sizes.h>
> +
> +#define FPGA_MIN_CFG_WAIT_US	10
> +
> +struct xilinx_spi_conf {
> +	struct spi_device *spi;
> +	struct gpio_desc *prog_b;
> +	struct gpio_desc *done;
> +};
> +
> +static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
> +{
> +	struct xilinx_spi_conf *conf = mgr->priv;
> +
> +	if (!gpiod_get_value(conf->done))
> +		return FPGA_MGR_STATE_RESET;
> +
> +	return FPGA_MGR_STATE_UNKNOWN;
> +}
> +
> +static int xilinx_spi_write_init(struct fpga_manager *mgr,
> +				 struct fpga_image_info *info,
> +				 const char *buf, size_t count)
> +{
> +	struct xilinx_spi_conf *conf = mgr->priv;
> +	const size_t prog_latency_1000us = 1000;
> +	const size_t prog_pulse_1us = 1;
> +
> +	if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
> +		dev_err(&mgr->dev, "Partial reconfiguration not supported.\n");
> +		return -EINVAL;
> +	}
> +
> +	gpiod_set_value(conf->prog_b, 1);
> +
> +	udelay(prog_pulse_1us); /* min is 500 ns */
> +
> +	gpiod_set_value(conf->prog_b, 0);
> +
> +	if (gpiod_get_value(conf->done)) {
> +		dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
> +		return -EIO;
> +	}
> +
> +	/* program latency */
> +	usleep_range(prog_latency_1000us, prog_latency_1000us + 500);

Based on my colleague for spartan6 this should be 5ms and other xilinx
fpgas can take up to 7.5ms.

In general, it is better to poll for INIT_B pin==High (but that takes
another GPIO) and wait until at least 10 ms before timeout.


> +	return 0;
> +}
> +
> +static int xilinx_spi_write(struct fpga_manager *mgr, const char *buf,
> +			    size_t count)
> +{
> +	struct xilinx_spi_conf *conf = mgr->priv;
> +	const char *fw_data = buf;
> +	const char *fw_data_end = fw_data + count;
> +
> +	while (fw_data < fw_data_end) {
> +		size_t remaining, stride;
> +		int ret;
> +
> +		remaining = fw_data_end - fw_data;
> +		stride = min_t(size_t, remaining, SZ_4K);
> +
> +		ret = spi_write(conf->spi, fw_data, stride);
> +		if (ret) {
> +			dev_err(&mgr->dev, "SPI error in firmware write: %d\n",
> +				ret);
> +			return ret;
> +		}
> +		fw_data += stride;
> +	}
> +
> +	return 0;
> +}
> +
> +static int xilinx_spi_write_complete(struct fpga_manager *mgr,
> +				     struct fpga_image_info *info)
> +{
> +	struct xilinx_spi_conf *conf = mgr->priv;
> +	int wait;
> +
> +	if (gpiod_get_value(conf->done))
> +		return 0;
> +
> +	wait = info->config_complete_timeout_us / FPGA_MIN_CFG_WAIT_US;
> +	if (info->config_complete_timeout_us % FPGA_MIN_CFG_WAIT_US)
> +		wait += 1;
> +
> +	while (wait--) {
> +		usleep_range(FPGA_MIN_CFG_WAIT_US, FPGA_MIN_CFG_WAIT_US + 5);
> +
> +		if (gpiod_get_value(conf->done))
> +			return 0;
> +	}
> +

Based on my colleague:
IMHO, for step 4 it is better to do these steps to cover more possible
configuration DONE scenarios:

While ((DONE==0) and (NOT TIMEOUT)) {
    Continue to apply CCLK cycles;
    Check DONE;
    timeout++;
}

Apply at least 8 more CCLK cycles.

The timeout should be equivalent to at least 10 ms of time.

Thanks,
Michal

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Re: [PATCH v3 2/2] fpga manager: Add Xilinx slave serial SPI driver

[Anatolij Gustschin]

On Wed, 22 Feb 2017 16:04:47 +0100
Michal Simek michal.simek-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org wrote:
...
>> +	/* program latency */
>> +	usleep_range(prog_latency_1000us, prog_latency_1000us + 500);  
>
>Based on my colleague for spartan6 this should be 5ms and other xilinx
>fpgas can take up to 7.5ms.
>
>In general, it is better to poll for INIT_B pin==High (but that takes
>another GPIO) and wait until at least 10 ms before timeout.

checked in the ug380.pdf, it depends on the speed grade, for some
spartan6 it can be max. 4ms, for others 5ms. It is a max. value,
INIT_B can go high earlier, but in my hw setup INIT_B is not
connected. Someone with a hw setup with INIT_B connected can
add optional support for INIT_P polling.

...
>> +static int xilinx_spi_write_complete(struct fpga_manager *mgr,
>> +				     struct fpga_image_info *info)
>> +{
>> +	struct xilinx_spi_conf *conf = mgr->priv;
>> +	int wait;
>> +
>> +	if (gpiod_get_value(conf->done))
>> +		return 0;
>> +
>> +	wait = info->config_complete_timeout_us / FPGA_MIN_CFG_WAIT_US;
>> +	if (info->config_complete_timeout_us % FPGA_MIN_CFG_WAIT_US)
>> +		wait += 1;
>> +
>> +	while (wait--) {
>> +		usleep_range(FPGA_MIN_CFG_WAIT_US, FPGA_MIN_CFG_WAIT_US + 5);
>> +
>> +		if (gpiod_get_value(conf->done))
>> +			return 0;
>> +	}
>> +  
>
>Based on my colleague:
>IMHO, for step 4 it is better to do these steps to cover more possible
>configuration DONE scenarios:
>
>While ((DONE==0) and (NOT TIMEOUT)) {
>    Continue to apply CCLK cycles;
>    Check DONE;
>    timeout++;
>}
>
>Apply at least 8 more CCLK cycles.
>
>The timeout should be equivalent to at least 10 ms of time.

You mead Step 8 I think, not step 4. Will see what I can change.

Thansk,
Anatolij
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Re: [PATCH v3 2/2] fpga manager: Add Xilinx slave serial SPI driver

[Michal Simek]

On 23.2.2017 10:28, Anatolij Gustschin wrote:
> On Wed, 22 Feb 2017 16:04:47 +0100
> Michal Simek michal.simek-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org wrote:
> ...
>>> +	/* program latency */
>>> +	usleep_range(prog_latency_1000us, prog_latency_1000us + 500);  
>>
>> Based on my colleague for spartan6 this should be 5ms and other xilinx
>> fpgas can take up to 7.5ms.
>>
>> In general, it is better to poll for INIT_B pin==High (but that takes
>> another GPIO) and wait until at least 10 ms before timeout.
> 
> checked in the ug380.pdf, it depends on the speed grade, for some
> spartan6 it can be max. 4ms, for others 5ms. It is a max. value,
> INIT_B can go high earlier, but in my hw setup INIT_B is not
> connected. Someone with a hw setup with INIT_B connected can
> add optional support for INIT_P polling.
> 
> ...
>>> +static int xilinx_spi_write_complete(struct fpga_manager *mgr,
>>> +				     struct fpga_image_info *info)
>>> +{
>>> +	struct xilinx_spi_conf *conf = mgr->priv;
>>> +	int wait;
>>> +
>>> +	if (gpiod_get_value(conf->done))
>>> +		return 0;
>>> +
>>> +	wait = info->config_complete_timeout_us / FPGA_MIN_CFG_WAIT_US;
>>> +	if (info->config_complete_timeout_us % FPGA_MIN_CFG_WAIT_US)
>>> +		wait += 1;
>>> +
>>> +	while (wait--) {
>>> +		usleep_range(FPGA_MIN_CFG_WAIT_US, FPGA_MIN_CFG_WAIT_US + 5);
>>> +
>>> +		if (gpiod_get_value(conf->done))
>>> +			return 0;
>>> +	}
>>> +  
>>
>> Based on my colleague:
>> IMHO, for step 4 it is better to do these steps to cover more possible
>> configuration DONE scenarios:
>>
>> While ((DONE==0) and (NOT TIMEOUT)) {
>>    Continue to apply CCLK cycles;
>>    Check DONE;
>>    timeout++;
>> }
>>
>> Apply at least 8 more CCLK cycles.
>>
>> The timeout should be equivalent to at least 10 ms of time.
> 
> You mead Step 8 I think, not step 4. Will see what I can change.

This was just c&p from his reply with different steps numbers. :-)

Thanks,
Michal


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Re: [PATCH v3 1/2] dt: bindings: fpga: add xilinx slave-serial binding description

[Rob Herring]

On Wed, Feb 22, 2017 at 11:39:10AM +0100, Anatolij Gustschin wrote:
> Add dt binding documentation details for Xilinx FPGA configuration
> over slave serial interface.
> 
> Signed-off-by: Anatolij Gustschin <agust-ynQEQJNshbs@public.gmane.org>
> ---
> Changes in v3:
> 
>  - extend example to show the usage in SPI master node, connected
>    to the fpga-region node
> 
> Changes in v2:
> 
>  - correct gpios properties in example to match above description
> 
>  - use fpga-mgr@0 instead of fpga-spi@0 in example
> 
>  .../bindings/fpga/xilinx-slave-serial.txt          | 44 ++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/fpga/xilinx-slave-serial.txt

Acked-by: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
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