[Qemu-devel] [PATCH arm-devs v1 09/15] xilinx_spips: Implement automatic CS

[Peter Crosthwaite <peter.crosthwaite@xilinx.com>]

Implement the automatic CS control feature. If the MANUAL_CS bit is
cleared then the chip select stay de-asserted as long as the tx FIFO
is empty.

Signed-off-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
---

 hw/xilinx_spips.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/hw/xilinx_spips.c b/hw/xilinx_spips.c
index f7d942e..16c2e1d 100644
--- a/hw/xilinx_spips.c
+++ b/hw/xilinx_spips.c
@@ -177,6 +177,12 @@ static inline int num_effective_busses(XilinxSPIPS *s)
             s->regs[R_LQSPI_CFG] & LQSPI_CFG_TWO_MEM) ? s->num_busses : 1;
 }
 
+static inline bool xilinx_spips_cs_is_set(XilinxSPIPS *s, int i, int field)
+{
+    return ~field & (1 << i) && (s->regs[R_CONFIG] & MANUAL_CS
+                    || !fifo8_is_empty(&s->tx_fifo));
+}
+
 static void xilinx_spips_update_cs_lines(XilinxSPIPS *s)
 {
     int i, j;
@@ -189,14 +195,14 @@ static void xilinx_spips_update_cs_lines(XilinxSPIPS *s)
             int cs_to_set = (j * s->num_cs + i + upage) %
                                 (s->num_cs * s->num_busses);
 
-            if (~field & (1 << i) && !found) {
+            if (xilinx_spips_cs_is_set(s, i, field) && !found) {
                 DB_PRINT("selecting slave %d\n", i);
                 qemu_set_irq(s->cs_lines[cs_to_set], 0);
             } else {
                 qemu_set_irq(s->cs_lines[cs_to_set], 1);
             }
         }
-        if (~field & (1 << i)) {
+        if (xilinx_spips_cs_is_set(s, i, field)) {
             found = true;
         }
     }
@@ -487,7 +493,7 @@ lqspi_read(void *opaque, hwaddr addr, unsigned int size)
         fifo8_reset(&s->rx_fifo);
 
         s->regs[R_CONFIG] &= ~CS;
-        s->regs[R_CONFIG] |= (~(1 << slave) << CS_SHIFT) & CS;
+        s->regs[R_CONFIG] |= ((~(1 << slave) << CS_SHIFT) & CS) | MANUAL_CS;
         xilinx_spips_update_cs_lines(s);
 
         /* instruction */
-- 
1.7.0.4