1 files changed, 276 insertions, 0 deletions
diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
new file mode 100644
index 000000000..e1a227e7f
--- /dev/null
+++ b/drivers/fpga/xilinx-spi.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Xilinx Spartan6 and 7 Series Slave Serial SPI Driver
+ *
+ * Copyright (C) 2017 DENX Software Engineering
+ *
+ * Anatolij Gustschin <agust@denx.de>
+ *
+ * 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>
+
+struct xilinx_spi_conf {
+	struct spi_device *spi;
+	struct gpio_desc *prog_b;
+	struct gpio_desc *init_b;
+	struct gpio_desc *done;
+};
+
+static int get_done_gpio(struct fpga_manager *mgr)
+{
+	struct xilinx_spi_conf *conf = mgr->priv;
+	int ret;
+
+	ret = gpiod_get_value(conf->done);
+
+	if (ret < 0)
+		dev_err(&mgr->dev, "Error reading DONE (%d)\n", ret);
+
+	return ret;
+}
+
+static enum fpga_mgr_states xilinx_spi_state(struct fpga_manager *mgr)
+{
+	if (!get_done_gpio(mgr))
+		return FPGA_MGR_STATE_RESET;
+
+	return FPGA_MGR_STATE_UNKNOWN;
+}
+
+/**
+ * wait_for_init_b - wait for the INIT_B pin to have a given state, or wait
+ * a given delay if the pin is unavailable
+ *
+ * @mgr:        The FPGA manager object
+ * @value:      Value INIT_B to wait for (1 = asserted = low)
+ * @alt_udelay: Delay to wait if the INIT_B GPIO is not available
+ *
+ * Returns 0 when the INIT_B GPIO reached the given state or -ETIMEDOUT if
+ * too much time passed waiting for that. If no INIT_B GPIO is available
+ * then always return 0.
+ */
+static int wait_for_init_b(struct fpga_manager *mgr, int value,
+			   unsigned long alt_udelay)
+{
+	struct xilinx_spi_conf *conf = mgr->priv;
+	unsigned long timeout = jiffies + msecs_to_jiffies(1000);
+
+	if (conf->init_b) {
+		while (time_before(jiffies, timeout)) {
+			int ret = gpiod_get_value(conf->init_b);
+
+			if (ret == value)
+				return 0;
+
+			if (ret < 0) {
+				dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
+				return ret;
+			}
+
+			usleep_range(100, 400);
+		}
+
+		dev_err(&mgr->dev, "Timeout waiting for INIT_B to %s\n",
+			value ? "assert" : "deassert");
+		return -ETIMEDOUT;
+	}
+
+	udelay(alt_udelay);
+
+	return 0;
+}
+
+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;
+	int err;
+
+	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);
+
+	err = wait_for_init_b(mgr, 1, 1); /* min is 500 ns */
+	if (err) {
+		gpiod_set_value(conf->prog_b, 0);
+		return err;
+	}
+
+	gpiod_set_value(conf->prog_b, 0);
+
+	err = wait_for_init_b(mgr, 0, 0);
+	if (err)
+		return err;
+
+	if (get_done_gpio(mgr)) {
+		dev_err(&mgr->dev, "Unexpected DONE pin state...\n");
+		return -EIO;
+	}
+
+	/* program latency */
+	usleep_range(7500, 7600);
+	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_apply_cclk_cycles(struct xilinx_spi_conf *conf)
+{
+	struct spi_device *spi = conf->spi;
+	const u8 din_data[1] = { 0xff };
+	int ret;
+
+	ret = spi_write(conf->spi, din_data, sizeof(din_data));
+	if (ret)
+		dev_err(&spi->dev, "applying CCLK cycles failed: %d\n", ret);
+
+	return ret;
+}
+
+static int xilinx_spi_write_complete(struct fpga_manager *mgr,
+				     struct fpga_image_info *info)
+{
+	struct xilinx_spi_conf *conf = mgr->priv;
+	unsigned long timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us);
+	bool expired = false;
+	int done;
+	int ret;
+
+	/*
+	 * This loop is carefully written such that if the driver is
+	 * scheduled out for more than 'timeout', we still check for DONE
+	 * before giving up and we apply 8 extra CCLK cycles in all cases.
+	 */
+	while (!expired) {
+		expired = time_after(jiffies, timeout);
+
+		done = get_done_gpio(mgr);
+		if (done < 0)
+			return done;
+
+		ret = xilinx_spi_apply_cclk_cycles(conf);
+		if (ret)
+			return ret;
+
+		if (done)
+			return 0;
+	}
+
+	if (conf->init_b) {
+		ret = gpiod_get_value(conf->init_b);
+
+		if (ret < 0) {
+			dev_err(&mgr->dev, "Error reading INIT_B (%d)\n", ret);
+			return ret;
+		}
+
+		dev_err(&mgr->dev,
+			ret ? "CRC error or invalid device\n"
+			: "Missing sync word or incomplete bitstream\n");
+	} else {
+		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;
+	struct fpga_manager *mgr;
+
+	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))
+		return dev_err_probe(&spi->dev, PTR_ERR(conf->prog_b),
+				     "Failed to get PROGRAM_B gpio\n");
+
+	conf->init_b = devm_gpiod_get_optional(&spi->dev, "init-b", GPIOD_IN);
+	if (IS_ERR(conf->init_b))
+		return dev_err_probe(&spi->dev, PTR_ERR(conf->init_b),
+				     "Failed to get INIT_B gpio\n");
+
+	conf->done = devm_gpiod_get(&spi->dev, "done", GPIOD_IN);
+	if (IS_ERR(conf->done))
+		return dev_err_probe(&spi->dev, PTR_ERR(conf->done),
+				     "Failed to get DONE gpio\n");
+
+	mgr = devm_fpga_mgr_register(&spi->dev,
+				     "Xilinx Slave Serial FPGA Manager",
+				     &xilinx_spi_ops, conf);
+	return PTR_ERR_OR_ZERO(mgr);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id xlnx_spi_of_match[] = {
+	{ .compatible = "xlnx,fpga-slave-serial", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, xlnx_spi_of_match);
+#endif
+
+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,
+};
+
+module_spi_driver(xilinx_slave_spi_driver)
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Anatolij Gustschin <agust@denx.de>");
+MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SPI");