fpga manager: Add Xilinx slave serial SPI driver

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

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Moritz Fischer <mdf@kernel.org>
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 198 insertions, 0 deletions

diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
new file mode 100644
index 000000000000..9b62a4c2a3df
--- /dev/null
+++ b/drivers/fpga/xilinx-spi.c
@@ -0,0 +1,198 @@
+/*
+ * Xilinx Spartan6 Slave Serial SPI Driver
+ *
+ * Copyright (C) 2017 DENX Software Engineering
+ *
+ * Anatolij Gustschin <agust@denx.de>
+ *
+ * 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>
+
+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_7500us = 7500;
+        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_7500us, prog_latency_7500us + 100);
+        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;
+        int ret;
+
+        if (gpiod_get_value(conf->done))
+                return xilinx_spi_apply_cclk_cycles(conf);
+
+        timeout = jiffies + usecs_to_jiffies(info->config_complete_timeout_us);
+
+        while (time_before(jiffies, timeout)) {
+
+                ret = xilinx_spi_apply_cclk_cycles(conf);
+                if (ret)
+                        return ret;
+
+                if (gpiod_get_value(conf->done))
+                        return xilinx_spi_apply_cclk_cycles(conf);
+        }
+
+        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@denx.de>");
+MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SPI");