fpga manager: Add altera-ps-spi driver for Altera FPGAs

altera-ps-spi loads FPGA firmware over SPI, using the "passive serial"
interface on Altera Arria 10, Cyclone V or Stratix V FPGAs.

This is one of the simpler ways to set up an FPGA at runtime.
The signal interface is close to unidirectional SPI with lsb first.

Signed-off-by: Joshua Clayton <stillcompiling@gmail.com>
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 305 insertions, 0 deletions

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index 10361902c830..e0e2d6db669f 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -24,6 +24,13 @@ config FPGA_MGR_ICE40_SPI
         help
           FPGA manager driver support for Lattice iCE40 FPGAs over SPI.
 
+config FPGA_MGR_ALTERA_PS_SPI
+        tristate "Altera FPGA Passive Serial over SPI"
+        depends on SPI
+        help
+          FPGA manager driver support for Altera Arria/Cyclone/Stratix
+          using the passive serial interface over SPI.
+
 config FPGA_MGR_SOCFPGA
         tristate "Altera SOCFPGA FPGA Manager"
         depends on ARCH_SOCFPGA || COMPILE_TEST
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index 2a4f0218145c..e75d3570e26a 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -6,6 +6,7 @@
 obj-$(CONFIG_FPGA)                      += fpga-mgr.o
 
 # FPGA Manager Drivers
+obj-$(CONFIG_FPGA_MGR_ALTERA_PS_SPI)    += altera-ps-spi.o
 obj-$(CONFIG_FPGA_MGR_ICE40_SPI)        += ice40-spi.o
 obj-$(CONFIG_FPGA_MGR_SOCFPGA)          += socfpga.o
 obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10)      += socfpga-a10.o
diff --git a/drivers/fpga/altera-ps-spi.c b/drivers/fpga/altera-ps-spi.c
new file mode 100644
index 000000000000..0db8def668ed
--- /dev/null
+++ b/drivers/fpga/altera-ps-spi.c
@@ -0,0 +1,297 @@
+/*
+ * Altera Passive Serial SPI Driver
+ *
+ *  Copyright (c) 2017 United Western Technologies, Corporation
+ *
+ *  Joshua Clayton <stillcompiling@gmail.com>
+ *
+ * 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 Altera FPGA firmware that is loaded over SPI using the passive
+ * serial configuration method.
+ * Firmware must be in binary "rbf" format.
+ * Works on Arria 10, Cyclone V and Stratix V. Should work on Cyclone series.
+ * May work on other Altera FPGAs.
+ */
+
+#include <linux/bitrev.h>
+#include <linux/delay.h>
+#include <linux/fpga/fpga-mgr.h>
+#include <linux/gpio/consumer.h>
+#include <linux/module.h>
+#include <linux/of_gpio.h>
+#include <linux/of_device.h>
+#include <linux/spi/spi.h>
+#include <linux/sizes.h>
+
+enum altera_ps_devtype {
+        CYCLONE5,
+        ARRIA10,
+};
+
+struct altera_ps_data {
+        enum altera_ps_devtype devtype;
+        int status_wait_min_us;
+        int status_wait_max_us;
+        int t_cfg_us;
+        int t_st2ck_us;
+};
+
+struct altera_ps_conf {
+        struct gpio_desc *config;
+        struct gpio_desc *confd;
+        struct gpio_desc *status;
+        struct spi_device *spi;
+        const struct altera_ps_data *data;
+        u32 info_flags;
+        char mgr_name[64];
+};
+
+/*          |   Arria 10  |   Cyclone5  |   Stratix5  |
+ * t_CF2ST0 |     [; 600] |     [; 600] |     [; 600] |ns
+ * t_CFG    |        [2;] |        [2;] |        [2;] |µs
+ * t_STATUS | [268; 3000] | [268; 1506] | [268; 1506] |µs
+ * t_CF2ST1 |    [; 3000] |    [; 1506] |    [; 1506] |µs
+ * t_CF2CK  |     [3010;] |     [1506;] |     [1506;] |µs
+ * t_ST2CK  |       [10;] |        [2;] |        [2;] |µs
+ * t_CD2UM  |  [175; 830] |  [175; 437] |  [175; 437] |µs
+ */
+static struct altera_ps_data c5_data = {
+        /* these values for Cyclone5 are compatible with Stratix5 */
+        .devtype = CYCLONE5,
+        .status_wait_min_us = 268,
+        .status_wait_max_us = 1506,
+        .t_cfg_us = 2,
+        .t_st2ck_us = 2,
+};
+
+static struct altera_ps_data a10_data = {
+        .devtype = ARRIA10,
+        .status_wait_min_us = 268,  /* min(t_STATUS) */
+        .status_wait_max_us = 3000, /* max(t_CF2ST1) */
+        .t_cfg_us = 2,    /* max { min(t_CFG), max(tCF2ST0) } */
+        .t_st2ck_us = 10, /* min(t_ST2CK) */
+};
+
+static const struct of_device_id of_ef_match[] = {
+        { .compatible = "altr,fpga-passive-serial", .data = &c5_data },
+        { .compatible = "altr,fpga-arria10-passive-serial", .data = &a10_data },
+        {}
+};
+MODULE_DEVICE_TABLE(of, of_ef_match);
+
+static enum fpga_mgr_states altera_ps_state(struct fpga_manager *mgr)
+{
+        struct altera_ps_conf *conf = mgr->priv;
+
+        if (gpiod_get_value_cansleep(conf->status))
+                return FPGA_MGR_STATE_RESET;
+
+        return FPGA_MGR_STATE_UNKNOWN;
+}
+
+static inline void altera_ps_delay(int delay_us)
+{
+        if (delay_us > 10)
+                usleep_range(delay_us, delay_us + 5);
+        else
+                udelay(delay_us);
+}
+
+static int altera_ps_write_init(struct fpga_manager *mgr,
+                                struct fpga_image_info *info,
+                                const char *buf, size_t count)
+{
+        struct altera_ps_conf *conf = mgr->priv;
+        int min, max, waits;
+        int i;
+
+        conf->info_flags = info->flags;
+
+        if (info->flags & FPGA_MGR_PARTIAL_RECONFIG) {
+                dev_err(&mgr->dev, "Partial reconfiguration not supported.\n");
+                return -EINVAL;
+        }
+
+        gpiod_set_value_cansleep(conf->config, 1);
+
+        /* wait min reset pulse time */
+        altera_ps_delay(conf->data->t_cfg_us);
+
+        if (!gpiod_get_value_cansleep(conf->status)) {
+                dev_err(&mgr->dev, "Status pin failed to show a reset\n");
+                return -EIO;
+        }
+
+        gpiod_set_value_cansleep(conf->config, 0);
+
+        min = conf->data->status_wait_min_us;
+        max = conf->data->status_wait_max_us;
+        waits = max / min;
+        if (max % min)
+                waits++;
+
+        /* wait for max { max(t_STATUS), max(t_CF2ST1) } */
+        for (i = 0; i < waits; i++) {
+                usleep_range(min, min + 10);
+                if (!gpiod_get_value_cansleep(conf->status)) {
+                        /* wait for min(t_ST2CK)*/
+                        altera_ps_delay(conf->data->t_st2ck_us);
+                        return 0;
+                }
+        }
+
+        dev_err(&mgr->dev, "Status pin not ready.\n");
+        return -EIO;
+}
+
+static void rev_buf(char *buf, size_t len)
+{
+        const char *fw_end = (buf + len);
+
+        /* set buffer to lsb first */
+        while (buf < fw_end) {
+                *buf = bitrev8(*buf);
+                buf++;
+        }
+}
+
+static int altera_ps_write(struct fpga_manager *mgr, const char *buf,
+                           size_t count)
+{
+        struct altera_ps_conf *conf = mgr->priv;
+        const char *fw_data = buf;
+        const char *fw_data_end = fw_data + count;
+
+        while (fw_data < fw_data_end) {
+                int ret;
+                size_t stride = min_t(size_t, fw_data_end - fw_data, SZ_4K);
+
+                if (!(conf->info_flags & FPGA_MGR_BITSTREAM_LSB_FIRST))
+                        rev_buf((char *)fw_data, stride);
+
+                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 altera_ps_write_complete(struct fpga_manager *mgr,
+                                    struct fpga_image_info *info)
+{
+        struct altera_ps_conf *conf = mgr->priv;
+        const char dummy[] = {0};
+        int ret;
+
+        if (gpiod_get_value_cansleep(conf->status)) {
+                dev_err(&mgr->dev, "Error during configuration.\n");
+                return -EIO;
+        }
+
+        if (!IS_ERR(conf->confd)) {
+                if (!gpiod_get_raw_value_cansleep(conf->confd)) {
+                        dev_err(&mgr->dev, "CONF_DONE is inactive!\n");
+                        return -EIO;
+                }
+        }
+
+        /*
+         * After CONF_DONE goes high, send two additional falling edges on DCLK
+         * to begin initialization and enter user mode
+         */
+        ret = spi_write(conf->spi, dummy, 1);
+        if (ret) {
+                dev_err(&mgr->dev, "spi error during end sequence: %d\n", ret);
+                return ret;
+        }
+
+        return 0;
+}
+
+static const struct fpga_manager_ops altera_ps_ops = {
+        .state = altera_ps_state,
+        .write_init = altera_ps_write_init,
+        .write = altera_ps_write,
+        .write_complete = altera_ps_write_complete,
+};
+
+static int altera_ps_probe(struct spi_device *spi)
+{
+        struct altera_ps_conf *conf;
+        const struct of_device_id *of_id;
+
+        conf = devm_kzalloc(&spi->dev, sizeof(*conf), GFP_KERNEL);
+        if (!conf)
+                return -ENOMEM;
+
+        of_id = of_match_device(of_ef_match, &spi->dev);
+        if (!of_id)
+                return -ENODEV;
+
+        conf->data = of_id->data;
+        conf->spi = spi;
+        conf->config = devm_gpiod_get(&spi->dev, "nconfig", GPIOD_OUT_HIGH);
+        if (IS_ERR(conf->config)) {
+                dev_err(&spi->dev, "Failed to get config gpio: %ld\n",
+                        PTR_ERR(conf->config));
+                return PTR_ERR(conf->config);
+        }
+
+        conf->status = devm_gpiod_get(&spi->dev, "nstat", GPIOD_IN);
+        if (IS_ERR(conf->status)) {
+                dev_err(&spi->dev, "Failed to get status gpio: %ld\n",
+                        PTR_ERR(conf->status));
+                return PTR_ERR(conf->status);
+        }
+
+        conf->confd = devm_gpiod_get(&spi->dev, "confd", GPIOD_IN);
+        if (IS_ERR(conf->confd)) {
+                dev_warn(&spi->dev, "Not using confd gpio: %ld\n",
+                         PTR_ERR(conf->confd));
+        }
+
+        /* Register manager with unique name */
+        snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s %s",
+                 dev_driver_string(&spi->dev), dev_name(&spi->dev));
+
+        return fpga_mgr_register(&spi->dev, conf->mgr_name,
+                                 &altera_ps_ops, conf);
+}
+
+static int altera_ps_remove(struct spi_device *spi)
+{
+        fpga_mgr_unregister(&spi->dev);
+
+        return 0;
+}
+
+static const struct spi_device_id altera_ps_spi_ids[] = {
+        {"cyclone-ps-spi", 0},
+        {}
+};
+MODULE_DEVICE_TABLE(spi, altera_ps_spi_ids);
+
+static struct spi_driver altera_ps_driver = {
+        .driver = {
+                .name = "altera-ps-spi",
+                .owner = THIS_MODULE,
+                .of_match_table = of_match_ptr(of_ef_match),
+        },
+        .id_table = altera_ps_spi_ids,
+        .probe = altera_ps_probe,
+        .remove = altera_ps_remove,
+};
+
+module_spi_driver(altera_ps_driver)
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Joshua Clayton <stillcompiling@gmail.com>");
+MODULE_DESCRIPTION("Module to load Altera FPGA firmware over SPI");