hw/misc/imx6ul_ccm: Implement non writable bits in CCM registers

Some bits of the CCM registers are non writable.

This was left undone in the initial commit (all bits of registers were
writable).

This patch adds the required code to protect the non writable bits.

Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
Message-id: 20200608133508.550046-1-jcd@tribudubois.net
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/misc/imx6ul_ccm.c

@@ -19,6 +19,62 @@
 
 #include "trace.h"
 
+static const uint32_t ccm_mask[CCM_MAX] = {
+    [CCM_CCR] = 0xf01fef80,
+    [CCM_CCDR] = 0xfffeffff,
+    [CCM_CSR] = 0xffffffff,
+    [CCM_CCSR] = 0xfffffef2,
+    [CCM_CACRR] = 0xfffffff8,
+    [CCM_CBCDR] = 0xc1f8e000,
+    [CCM_CBCMR] = 0xfc03cfff,
+    [CCM_CSCMR1] = 0x80700000,
+    [CCM_CSCMR2] = 0xe01ff003,
+    [CCM_CSCDR1] = 0xfe00c780,
+    [CCM_CS1CDR] = 0xfe00fe00,
+    [CCM_CS2CDR] = 0xf8007000,
+    [CCM_CDCDR] = 0xf00fffff,
+    [CCM_CHSCCDR] = 0xfffc01ff,
+    [CCM_CSCDR2] = 0xfe0001ff,
+    [CCM_CSCDR3] = 0xffffc1ff,
+    [CCM_CDHIPR] = 0xffffffff,
+    [CCM_CTOR] = 0x00000000,
+    [CCM_CLPCR] = 0xf39ff01c,
+    [CCM_CISR] = 0xfb85ffbe,
+    [CCM_CIMR] = 0xfb85ffbf,
+    [CCM_CCOSR] = 0xfe00fe00,
+    [CCM_CGPR] = 0xfffc3fea,
+    [CCM_CCGR0] = 0x00000000,
+    [CCM_CCGR1] = 0x00000000,
+    [CCM_CCGR2] = 0x00000000,
+    [CCM_CCGR3] = 0x00000000,
+    [CCM_CCGR4] = 0x00000000,
+    [CCM_CCGR5] = 0x00000000,
+    [CCM_CCGR6] = 0x00000000,
+    [CCM_CMEOR] = 0xafffff1f,
+};
+
+static const uint32_t analog_mask[CCM_ANALOG_MAX] = {
+    [CCM_ANALOG_PLL_ARM] = 0xfff60f80,
+    [CCM_ANALOG_PLL_USB1] = 0xfffe0fbc,
+    [CCM_ANALOG_PLL_USB2] = 0xfffe0fbc,
+    [CCM_ANALOG_PLL_SYS] = 0xfffa0ffe,
+    [CCM_ANALOG_PLL_SYS_SS] = 0x00000000,
+    [CCM_ANALOG_PLL_SYS_NUM] = 0xc0000000,
+    [CCM_ANALOG_PLL_SYS_DENOM] = 0xc0000000,
+    [CCM_ANALOG_PLL_AUDIO] = 0xffe20f80,
+    [CCM_ANALOG_PLL_AUDIO_NUM] = 0xc0000000,
+    [CCM_ANALOG_PLL_AUDIO_DENOM] = 0xc0000000,
+    [CCM_ANALOG_PLL_VIDEO] = 0xffe20f80,
+    [CCM_ANALOG_PLL_VIDEO_NUM] = 0xc0000000,
+    [CCM_ANALOG_PLL_VIDEO_DENOM] = 0xc0000000,
+    [CCM_ANALOG_PLL_ENET] = 0xffc20ff0,
+    [CCM_ANALOG_PFD_480] = 0x40404040,
+    [CCM_ANALOG_PFD_528] = 0x40404040,
+    [PMU_MISC0] = 0x01fe8306,
+    [PMU_MISC1] = 0x07fcede0,
+    [PMU_MISC2] = 0x005f5f5f,
+};
+
 static const char *imx6ul_ccm_reg_name(uint32_t reg)
 {
     static char unknown[20];
@@ -596,11 +652,8 @@ static void imx6ul_ccm_write(void *opaque, hwaddr offset, uint64_t value,
 
     trace_ccm_write_reg(imx6ul_ccm_reg_name(index), (uint32_t)value);
 
-    /*
-     * We will do a better implementation later. In particular some bits
-     * cannot be written to.
-     */
-    s->ccm[index] = (uint32_t)value;
+    s->ccm[index] = (s->ccm[index] & ccm_mask[index]) |
+                           ((uint32_t)value & ~ccm_mask[index]);
 }
 
 static uint64_t imx6ul_analog_read(void *opaque, hwaddr offset, unsigned size)
@@ -737,7 +790,7 @@ static void imx6ul_analog_write(void *opaque, hwaddr offset, uint64_t value,
          * the REG_NAME register. So we change the value of the
          * REG_NAME register, setting bits passed in the value.
          */
-        s->analog[index - 1] |= value;
+        s->analog[index - 1] |= (value & ~analog_mask[index - 1]);
         break;
     case CCM_ANALOG_PLL_ARM_CLR:
     case CCM_ANALOG_PLL_USB1_CLR:
@@ -762,7 +815,7 @@ static void imx6ul_analog_write(void *opaque, hwaddr offset, uint64_t value,
          * the REG_NAME register. So we change the value of the
          * REG_NAME register, unsetting bits passed in the value.
          */
-        s->analog[index - 2] &= ~value;
+        s->analog[index - 2] &= ~(value & ~analog_mask[index - 2]);
         break;
     case CCM_ANALOG_PLL_ARM_TOG:
     case CCM_ANALOG_PLL_USB1_TOG:
@@ -787,14 +840,11 @@ static void imx6ul_analog_write(void *opaque, hwaddr offset, uint64_t value,
          * the REG_NAME register. So we change the value of the
          * REG_NAME register, toggling bits passed in the value.
          */
-        s->analog[index - 3] ^= value;
+        s->analog[index - 3] ^= (value & ~analog_mask[index - 3]);
         break;
     default:
-        /*
-         * We will do a better implementation later. In particular some bits
-         * cannot be written to.
-         */
-        s->analog[index] = value;
+        s->analog[index] = (s->analog[index] & analog_mask[index]) |
+                           (value & ~analog_mask[index]);
         break;
     }
 }