powerpc/44x/fsp2: tvsense workaround for dd1

TVSENSE(temperature and voltage sensors) reset is blocked (clock gated)
by the POR default of the TVS sleep config bit. As a consequence,
TVSENSE will provide erratic sensor values, which may result in
spurious (parity) errors recorded in the CMU FIR and leading to
erroneous interrupt requests once the CMU interrupt is unmasked.
Purpose of this to set up CMU in working state in any cases even
in case of parity errors.
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Signed-off-by: Ivan Mikhaylov <ivan@de.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/platforms/44x/fsp2.c

@@ -59,6 +59,23 @@ static int __init fsp2_probe(void)
 	mtdcr(DCRN_PLB6_HD, 0xffff0000);
 	mtdcr(DCRN_PLB6_SHD, 0xffff0000);
 
+	/* TVSENSE reset is blocked (clock gated) by the POR default of the TVS
+	 * sleep config bit. As a consequence, TVSENSE will provide erratic
+	 * sensor values, which may result in spurious (parity) errors
+	 * recorded in the CMU FIR and leading to erroneous interrupt requests
+	 * once the CMU interrupt is unmasked.
+	 */
+
+	/* 1. set TVS1[UNDOZE] */
+	val = mfcmu(CMUN_TVS1);
+	val |= 0x4;
+	mtcmu(CMUN_TVS1, val);
+
+	/* 2. clear FIR[TVS] and FIR[TVSPAR] */
+	val = mfcmu(CMUN_FIR0);
+	val |= 0x30000000;
+	mtcmu(CMUN_FIR0, val);
+
 	/* L2 machine checks */
 	mtl2(L2PLBMCKEN0, 0xffffffff);
 	mtl2(L2PLBMCKEN1, 0x0000ffff);