[S] Change in coreboot[master]: mb/siemens/mc_apl5: Correct the Tx signal from SATA port 0

[Felix Held (Code Review)]

Felix Held has submitted this change. ( https://review.coreboot.org/c/coreboot/+/76175?usp=email )

Change subject: mb/siemens/mc_apl5: Correct the Tx signal from SATA port 0
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mb/siemens/mc_apl5: Correct the Tx signal from SATA port 0

Because of an incorrect transmit voltage swing, the signal must be
adjusted. The factor of slices for full swing level can be corrected via
the High Speed I/O Transmit Control Register 3. The appropriate value of
0.7 V was determined by using an oscilloscope.

Change-Id: I965960004ca44f1b37b16ce6484000fa7fd8ad90
Signed-off-by: Mario Scheithauer 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76175
Tested-by: build bot (Jenkins) 
Reviewed-by: Jan Samek 
Reviewed-by: Felix Singer 
---
M src/mainboard/siemens/mc_apl1/variants/mc_apl5/mainboard.c
1 file changed, 11 insertions(+), 0 deletions(-)

Approvals:
  Jan Samek: Looks good to me, approved
  build bot (Jenkins): Verified
  Felix Singer: Looks good to me, but someone else must approve

diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl5/mainboard.c b/src/mainboard/siemens/mc_apl1/variants/mc_apl5/mainboard.c
index 1e7fa37..8eedce6 100644
--- a/src/mainboard/siemens/mc_apl1/variants/mc_apl5/mainboard.c
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl5/mainboard.c
@@ -13,6 +13,9 @@
 #include <baseboard/variants.h>
 #include <types.h>

+#define TX_DWORD3_P0	0xc8c
+#define TX_SWING_MASK	0x00ff0000
+
 void variant_mainboard_final(void)
 {
    struct device *dev = NULL;
@@ -32,6 +35,14 @@
     */
    pcr_or32(PID_LPC, PCR_LPC_PRC, (PCR_LPC_CCE_EN | PCR_LPC_PCE_EN));

+	/*
+	 * Correct the SATA transmit signal via the High Speed I/O Transmit
+	 * Control Register 3 on SATA port 0.
+	 * Bit [23:16] sets the output voltage swing for TX line.
+	 * The value 0x5a sets the swing level to 0.7 V.
+	 */
+	pcr_rmw32(PID_MODPHY, TX_DWORD3_P0, ~TX_SWING_MASK, 0x5a << 16);
+
    /* Set Master Enable for on-board PCI device if allowed. */
    dev = dev_find_device(PCI_VID_SIEMENS, 0x403e, 0);
    if (dev) {