[sw] HAL: add TWI clock stretching

stnolting · Apr 1, 2024 · 91d9fc6 · 91d9fc6
1 parent 4f08418
commit 91d9fc6
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Showing 3 changed files with 13 additions and 5 deletions.
diff --git a/sw/lib/include/neorv32_twi.h b/sw/lib/include/neorv32_twi.h
@@ -65,6 +65,7 @@ enum NEORV32_TWI_CTRL_enum {
   TWI_CTRL_CDIV1    =  5, /**< TWI control register(5)  (r/w): Clock divider bit 1 */
   TWI_CTRL_CDIV2    =  6, /**< TWI control register(6)  (r/w): Clock divider bit 2 */
   TWI_CTRL_CDIV3    =  7, /**< TWI control register(7)  (r/w): Clock divider bit 3 */
+  TWI_CTRL_CLKSTR   =  8, /**< TWI control register(8)  (r/w): Enable/allow clock stretching */
 
   TWI_CTRL_FIFO_LSB = 15, /**< SPI control register(15) (r/-): log2(FIFO size), lsb */
   TWI_CTRL_FIFO_MSB = 18, /**< SPI control register(18) (r/-): log2(FIFO size), msb */
@@ -100,7 +101,7 @@ enum NEORV32_TWI_DCMD_enum {
  **************************************************************************/
 /**@{*/
 int  neorv32_twi_available(void);
-void neorv32_twi_setup(int prsc, int cdiv);
+void neorv32_twi_setup(int prsc, int cdiv, int clkstr);
 int  neorv32_twi_get_fifo_depth(void);
 void neorv32_twi_disable(void);
 void neorv32_twi_enable(void);

diff --git a/sw/lib/source/neorv32_twi.c b/sw/lib/source/neorv32_twi.c
@@ -64,15 +64,17 @@ int neorv32_twi_available(void) {
  *
  * @param[in] prsc Clock prescaler select (0..7). See #NEORV32_CLOCK_PRSC_enum.
  * @param[in] cdiv Clock divider (0..15).
+ * @param[in] clkstr Enable (allow) clock stretching.
  **************************************************************************/
-void neorv32_twi_setup(int prsc, int cdiv) {
+void neorv32_twi_setup(int prsc, int cdiv, int clkstr) {
 
   NEORV32_TWI->CTRL = 0; // reset
 
   uint32_t ctrl = 0;
-  ctrl |= ((uint32_t)(          1) << TWI_CTRL_EN);
-  ctrl |= ((uint32_t)(prsc & 0x07) << TWI_CTRL_PRSC0);
-  ctrl |= ((uint32_t)(cdiv & 0x0f) << TWI_CTRL_CDIV0);
+  ctrl |= ((uint32_t)(         0x1) << TWI_CTRL_EN);
+  ctrl |= ((uint32_t)(prsc   & 0x7) << TWI_CTRL_PRSC0);
+  ctrl |= ((uint32_t)(cdiv   & 0xf) << TWI_CTRL_CDIV0);
+  ctrl |= ((uint32_t)(clkstr & 0x1) << TWI_CTRL_CLKSTR);
   NEORV32_TWI->CTRL = ctrl;
 }
 

diff --git a/sw/svd/neorv32.svd b/sw/svd/neorv32.svd
@@ -1214,6 +1214,11 @@
               <bitRange>[7:4]</bitRange>
               <description>TWI clock divider</description>
             </field>
+            <field>
+              <name>TWI_CTRL_CLKSTR</name>
+              <bitRange>[8:8]</bitRange>
+              <description>Enable (allow) clock stretching</description>
+            </field>
             <field>
               <name>TWI_CTRL_FIFO</name>
               <bitRange>[18:15]</bitRange>