Add coding_rate field to LoraDataRate (+ fix 2.4GHz coding-rate).

Per Regional Parameters Specification, the LoRa modulation always uses
coding-rate 4/5, however this is not the case for ISM2400 (which is
currently not covered by the reg. params) in which case coding-rate
4/8LI must be used.

Closes #51.

chirpstack/src/downlink/helpers.rs

@@ -1,3 +1,5 @@
+use std::str::FromStr;
+
 use anyhow::Result;
 use rand::seq::SliceRandom;
 
@@ -65,7 +67,9 @@ pub fn set_tx_info_data_rate(
                 parameters: Some(gw::modulation::Parameters::Lora(gw::LoraModulationInfo {
                     bandwidth: v.bandwidth,
                     spreading_factor: v.spreading_factor as u32,
-                    code_rate: chirpstack_api::gw::CodeRate::Cr45.into(),
+                    code_rate: gw::CodeRate::from_str(&v.coding_rate)
+                        .map_err(|e| anyhow!("{}", e))?
+                        .into(),
                     polarization_inversion: true,
                     code_rate_legacy: "".into(),
                 })),

chirpstack/src/uplink/helpers.rs

@@ -25,6 +25,7 @@ pub fn get_uplink_dr(region_name: &str, tx_info: &chirpstack_api::gw::UplinkTxIn
             lrwn::region::DataRateModulation::Lora(lrwn::region::LoraDataRate {
                 spreading_factor: v.spreading_factor as u8,
                 bandwidth: v.bandwidth,
+                coding_rate: v.code_rate().into(),
             })
         }
         chirpstack_api::gw::modulation::Parameters::Fsk(v) => {
@@ -57,7 +58,9 @@ pub fn set_uplink_modulation(
                 gw::modulation::Parameters::Lora(gw::LoraModulationInfo {
                     bandwidth: v.bandwidth,
                     spreading_factor: v.spreading_factor as u32,
-                    code_rate: gw::CodeRate::Cr45.into(),
+                    code_rate: gw::CodeRate::from_str(&v.coding_rate)
+                        .map_err(|e| anyhow!("{}", e))?
+                        .into(),
                     code_rate_legacy: "".into(),
                     polarization_inversion: true,
                 })

chirpstack/src/uplink/stats.rs

@@ -255,6 +255,7 @@ fn per_modultation_to_per_dr(
                 lrwn::region::DataRateModulation::Lora(lrwn::region::LoraDataRate {
                     spreading_factor: v.spreading_factor as u8,
                     bandwidth: v.bandwidth,
+                    coding_rate: v.code_rate().into(),
                 })
             }
             gw::modulation::Parameters::Fsk(v) => {