host: SPI: Read number of supported SPI slaves from device

Add support for reading the number of supported SPI slaves from
the device. This has become necessary because we may have bitfiles
with different capabilities and we want to report this back correctly.

5 files changed, 51 insertions, 23 deletions

diff --git a/host/examples/spi.cpp b/host/examples/spi.cpp
index e5372cac3..e986eb7d3 100644
--- a/host/examples/spi.cpp
+++ b/host/examples/spi.cpp
@@ -68,8 +68,7 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
 
     // create a usrp device
     std::cout << std::endl;
-    std::cout << "Creating the usrp device with: " << args << "..."
-              << std::endl;
+    std::cout << "Creating the usrp device with: " << args << "..." << std::endl;
     auto usrp = uhd::usrp::multi_usrp::make(args);
 
     if (vm.count("list-banks")) {
@@ -80,7 +79,12 @@ int UHD_SAFE_MAIN(int argc, char* argv[])
         }
     }
 
-    // Get the SPI getter interface from where we'll get
+    // Get the SPI getter interface from where we'll get the SPI interface itself
+    if (!usrp->get_radio_control().has_feature<uhd::features::spi_getter_iface>()) {
+        std::cout << "Error: Could not find SPI_Getter_Iface. Please check if your FPGA "
+                     "image is up to date.\n";
+        return EXIT_FAILURE;
+    }
     auto& spi_getter_iface =
         usrp->get_radio_control().get_feature<uhd::features::spi_getter_iface>();
 
diff --git a/host/lib/include/uhdlib/usrp/cores/spi_core_4000.hpp b/host/lib/include/uhdlib/usrp/cores/spi_core_4000.hpp
index 4577b14cf..faeb9b03d 100644
--- a/host/lib/include/uhdlib/usrp/cores/spi_core_4000.hpp
+++ b/host/lib/include/uhdlib/usrp/cores/spi_core_4000.hpp
@@ -35,6 +35,7 @@ public:
         const size_t spi_transaction_cfg,
         const size_t spi_transaction_go,
         const size_t spi_status,
+        const size_t spi_controller_info,
         const mapper_sptr port_mapper);
 
     //! Configures the SPI transaction. The vector index refers to the slave number.
@@ -43,4 +44,3 @@ public:
 };
 
 }} // namespace uhd::cores
-
diff --git a/host/lib/usrp/cores/spi_core_4000.cpp b/host/lib/usrp/cores/spi_core_4000.cpp
index 1d72dd88d..55486d6c8 100644
--- a/host/lib/usrp/cores/spi_core_4000.cpp
+++ b/host/lib/usrp/cores/spi_core_4000.cpp
@@ -25,6 +25,7 @@ public:
         const size_t spi_transaction_cfg,
         const size_t spi_transaction_go,
         const size_t spi_status,
+        const size_t spi_controller_info,
         const mapper_sptr port_mapper)
         : _poke32(std::move(poke32_fn))
         , _peek32(std::move(peek32_fn))
@@ -32,6 +33,7 @@ public:
         , _spi_transaction_cfg(spi_transaction_cfg)
         , _spi_transaction_go(spi_transaction_go)
         , _spi_status(spi_status)
+        , _spi_ctrl_info(spi_controller_info)
         , _port_mapper(port_mapper)
     {
     }
@@ -39,12 +41,17 @@ public:
     void set_spi_slave_config(
         const std::vector<uhd::features::spi_slave_config_t>& ssc) override
     {
-        if (ssc.size() > 4) {
-            throw uhd::value_error(
-                "Passed more than 4 SPI slaves. Maximum number of SPI slaves is 4.");
+        const size_t num_slaves_allowed = _peek32(_spi_ctrl_info) & 0xF;
+        if (ssc.size() > num_slaves_allowed) {
+            throw uhd::value_error("Number of configurations passed ("
+                                   + std::to_string(ssc.size())
+                                   + ") exceeds the maximum number allowed by "
+                                     "the bitfile per radio block. Maximum number: "
+                                   + std::to_string(num_slaves_allowed));
         }
 
         _spi_slave_config = ssc;
+        _slave_ctrl_cache.assign(_spi_slave_config.size(), 0);
     }
 
     uint32_t transact_spi(const int which_slave,
@@ -135,8 +142,9 @@ private:
     const size_t _spi_transaction_cfg;
     const size_t _spi_transaction_go;
     const size_t _spi_status;
+    const size_t _spi_ctrl_info;
     const mapper_sptr _port_mapper;
-    std::vector<uint32_t> _slave_ctrl_cache{0, 0, 0, 0};
+    std::vector<uint32_t> _slave_ctrl_cache;
     uint32_t _transaction_cfg_cache = 0;
     std::mutex _mutex;
     std::vector<uhd::features::spi_slave_config_t> _spi_slave_config;
@@ -161,6 +169,7 @@ spi_core_4000::sptr spi_core_4000::make(spi_core_4000::poke32_fn_t&& poke32_fn,
     const size_t spi_transaction_cfg,
     const size_t spi_transaction_go,
     const size_t spi_status,
+    const size_t spi_controller_info,
     const mapper_sptr port_mapper)
 {
     return std::make_shared<spi_core_4000_impl>(std::move(poke32_fn),
@@ -169,6 +178,7 @@ spi_core_4000::sptr spi_core_4000::make(spi_core_4000::poke32_fn_t&& poke32_fn,
         spi_transaction_cfg,
         spi_transaction_go,
         spi_status,
+        spi_controller_info,
         port_mapper);
 }
 
diff --git a/host/lib/usrp/x400/x400_radio_control.cpp b/host/lib/usrp/x400/x400_radio_control.cpp
index ef2d6bd21..59207d486 100644
--- a/host/lib/usrp/x400/x400_radio_control.cpp
+++ b/host/lib/usrp/x400/x400_radio_control.cpp
@@ -191,20 +191,32 @@ x400_radio_control_impl::x400_radio_control_impl(make_args_ptr make_args)
 
         auto gpio_port_mapper = std::shared_ptr<uhd::mapper::gpio_port_mapper>(
             new uhd::rfnoc::x400::x400_gpio_port_mapping);
-        auto spicore = uhd::cores::spi_core_4000::make(
-            [this](const uint32_t addr, const uint32_t data) {
-                regs().poke32(addr, data, get_command_time(0));
-            },
-            [this](
-                const uint32_t addr) { return regs().peek32(addr, get_command_time(0)); },
-            x400_regs::SPI_SLAVE_CFG,
-            x400_regs::SPI_TRANSACTION_CFG_REG,
-            x400_regs::SPI_TRANSACTION_GO_REG,
-            x400_regs::SPI_STATUS_REG,
-            gpio_port_mapper);
-
-        _spi_getter_iface = std::make_shared<x400_spi_getter>(spicore);
-        register_feature(_spi_getter_iface);
+
+        // Check if SPI is available as GPIO source, otherwise don't register
+        // SPI_GETTER_IFace
+        auto gpio_srcs = _mb_control->get_gpio_srcs("GPIO0");
+        if (std::count(gpio_srcs.begin(), gpio_srcs.end(), "DB0_SPI") > 0) {
+            auto spicore = uhd::cores::spi_core_4000::make(
+                [this](const uint32_t addr, const uint32_t data) {
+                    regs().poke32(addr, data, get_command_time(0));
+                },
+                [this](const uint32_t addr) {
+                    return regs().peek32(addr, get_command_time(0));
+                },
+                x400_regs::SPI_SLAVE_CFG,
+                x400_regs::SPI_TRANSACTION_CFG_REG,
+                x400_regs::SPI_TRANSACTION_GO_REG,
+                x400_regs::SPI_STATUS_REG,
+                x400_regs::SPI_CONTROLLER_INFO_REG,
+                gpio_port_mapper);
+
+            _spi_getter_iface = std::make_shared<x400_spi_getter>(spicore);
+            register_feature(_spi_getter_iface);
+        } else {
+            UHD_LOG_INFO("x400_radio_control",
+                "SPI functionality not available in this FPGA image. Please update to at "
+                "least version 7.7 to use SPI.");
+        }
     }
 }
 
@@ -816,5 +828,4 @@ std::string x400_radio_control_impl::get_dboard_fe_from_chan(
 
 UHD_RFNOC_BLOCK_REGISTER_FOR_DEVICE_DIRECT(
     x400_radio_control, RADIO_BLOCK, X400, "Radio", true, "radio_clk", "ctrl_clk")
-
 }} // namespace uhd::rfnoc
diff --git a/host/lib/usrp/x400/x400_radio_control.hpp b/host/lib/usrp/x400/x400_radio_control.hpp
index cd45291bc..7fcf9a12a 100644
--- a/host/lib/usrp/x400/x400_radio_control.hpp
+++ b/host/lib/usrp/x400/x400_radio_control.hpp
@@ -54,6 +54,9 @@ constexpr uint32_t SPI_TRANSACTION_GO_REG = SPI_SLAVE_CFG + 0x0014;
 //! Base address for SPI_STATUS Register
 constexpr uint32_t SPI_STATUS_REG = SPI_SLAVE_CFG + 0x0018;
 
+//! Base address for SPI_CONTROLLER_INFO Register
+constexpr uint32_t SPI_CONTROLLER_INFO_REG = SPI_SLAVE_CFG + 0x001C;
+
 } // namespace x400_regs
 
 class x400_radio_control_impl : public radio_control_impl