bmips: enable the data Read Ahead Cache for BMIPS4350

The data RAC is left disabled by the bootloader in some SoCs, at least in
the core it boots from. Enabling this feature increases the performance up
to +30% depending on the task.

The kernel enables the whole RAC unconditionally on BMIPS3300 CPUs. Enable
the data RAC in a similar way also for BMIPS4350.

Tested on DGND3700 v1 (BCM6368) and HG556a (BCM6358).

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
(cherry picked from commit 6d1265b14850abaf8980e5cebef3e559b1fdcfb9)

diff --git a/target/linux/bmips/patches-5.15/204-mips-bmips-enable-RAC-on-BMIPS4350.patch b/target/linux/bmips/patches-5.15/204-mips-bmips-enable-RAC-on-BMIPS4350.patch
new file mode 100644 (file)
index 0000000..26bd03e
--- /dev/null
+++ b/target/linux/bmips/patches-5.15/204-mips-bmips-enable-RAC-on-BMIPS4350.patch
@@ -0,0 +1,42 @@
+From 7f862eaedac56b67972393f0a9affcd2fe53479b Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Daniel=20Gonz=C3=A1lez=20Cabanelas?= <dgcbueu@gmail.com>
+Date: Sun, 18 Jun 2023 19:59:25 +0200
+Subject: [PATCH] mips: bmips: enable RAC on BMIPS4350
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+The data RAC is left disabled by the bootloader in some SoCs, at least in
+the core it boots from.
+Enabling this feature increases the performance up to +30% depending on the
+task.
+
+Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
+Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
+---
+ arch/mips/kernel/smp-bmips.c | 14 ++++++++++++++
+ 1 file changed, 14 insertions(+)
+
+--- a/arch/mips/kernel/smp-bmips.c
++++ b/arch/mips/kernel/smp-bmips.c
+@@ -614,6 +614,20 @@ void bmips_cpu_setup(void)
+               __raw_readl(cbr + BMIPS_RAC_ADDRESS_RANGE);
+               break;
+ 
++      case CPU_BMIPS4350:
++              /* Enable data RAC */
++              if (!(read_c0_brcm_cmt_local() & (1 << 31))) {
++                      cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
++                      __raw_writel(cfg | 0xa, cbr + BMIPS_RAC_CONFIG);
++                      __raw_readl(cbr + BMIPS_RAC_CONFIG);
++              } else {
++                      cbr = (void __iomem *)0xff400000;
++                      cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG_1);
++                      __raw_writel(cfg | 0xa, cbr + BMIPS_RAC_CONFIG_1);
++                      __raw_readl(cbr + BMIPS_RAC_CONFIG_1);
++              }
++              break;
++
+       case CPU_BMIPS4380:
+               /* CBG workaround for early BMIPS4380 CPUs */
+               switch (read_c0_prid()) {