davinci: Support various speedgrades for MityDSP-L138 and MityARM-1808 SoMs

For the MityDSP-L138/MityARM-1808 SoMs, the speed grade can be determined
from the part number string read from the factory configuration block on
the on-board I2C PROM.  Configure the maximum CPU speed based on this
information.

This patch was tested using a MityDSP-L138 and MityARM-1808 at various
speedgrades.  Also, for code coverage, a bogus configuration was tested
as well as a configuration having an unknown part number.

Signed-off-by: Michael Williamson <michael.williamson@criticallink.com>
Tested-by: Michael Williamson <michael.williamson@criticallink.com>
Reviewed-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>

1 files changed, 75 insertions, 8 deletions

diff --git a/arch/arm/mach-davinci/board-mityomapl138.c b/arch/arm/mach-davinci/board-mityomapl138.c
index 0bb5f0ce4fdc..0ea59327dc28 100644
--- a/arch/arm/mach-davinci/board-mityomapl138.c
+++ b/arch/arm/mach-davinci/board-mityomapl138.c
@@ -44,38 +44,109 @@ struct factory_config {
 
 static struct factory_config factory_config;
 
+struct part_no_info {
+        const char      *part_no;       /* part number string of interest */
+        int             max_freq;       /* khz */
+};
+
+static struct part_no_info mityomapl138_pn_info[] = {
+        {
+                .part_no        = "L138-C",
+                .max_freq       = 300000,
+        },
+        {
+                .part_no        = "L138-D",
+                .max_freq       = 375000,
+        },
+        {
+                .part_no        = "L138-F",
+                .max_freq       = 456000,
+        },
+        {
+                .part_no        = "1808-C",
+                .max_freq       = 300000,
+        },
+        {
+                .part_no        = "1808-D",
+                .max_freq       = 375000,
+        },
+        {
+                .part_no        = "1808-F",
+                .max_freq       = 456000,
+        },
+        {
+                .part_no        = "1810-D",
+                .max_freq       = 375000,
+        },
+};
+
+#ifdef CONFIG_CPU_FREQ
+static void mityomapl138_cpufreq_init(const char *partnum)
+{
+        int i, ret;
+
+        for (i = 0; partnum && i < ARRAY_SIZE(mityomapl138_pn_info); i++) {
+                /*
+                 * the part number has additional characters beyond what is
+                 * stored in the table.  This information is not needed for
+                 * determining the speed grade, and would require several
+                 * more table entries.  Only check the first N characters
+                 * for a match.
+                 */
+                if (!strncmp(partnum, mityomapl138_pn_info[i].part_no,
+                             strlen(mityomapl138_pn_info[i].part_no))) {
+                        da850_max_speed = mityomapl138_pn_info[i].max_freq;
+                        break;
+                }
+        }
+
+        ret = da850_register_cpufreq("pll0_sysclk3");
+        if (ret)
+                pr_warning("cpufreq registration failed: %d\n", ret);
+}
+#else
+static void mityomapl138_cpufreq_init(const char *partnum) { }
+#endif
+
 static void read_factory_config(struct memory_accessor *a, void *context)
 {
         int ret;
+        const char *partnum = NULL;
         struct davinci_soc_info *soc_info = &davinci_soc_info;
 
         ret = a->read(a, (char *)&factory_config, 0, sizeof(factory_config));
         if (ret != sizeof(struct factory_config)) {
                 pr_warning("MityOMAPL138: Read Factory Config Failed: %d\n",
                                 ret);
-                return;
+                goto bad_config;
         }
 
         if (factory_config.magic != FACTORY_CONFIG_MAGIC) {
                 pr_warning("MityOMAPL138: Factory Config Magic Wrong (%X)\n",
                                 factory_config.magic);
-                return;
+                goto bad_config;
         }
 
         if (factory_config.version != FACTORY_CONFIG_VERSION) {
                 pr_warning("MityOMAPL138: Factory Config Version Wrong (%X)\n",
                                 factory_config.version);
-                return;
+                goto bad_config;
         }
 
         pr_info("MityOMAPL138: Found MAC = %pM\n", factory_config.mac);
-        pr_info("MityOMAPL138: Part Number = %s\n", factory_config.partnum);
         if (is_valid_ether_addr(factory_config.mac))
                 memcpy(soc_info->emac_pdata->mac_addr,
                         factory_config.mac, ETH_ALEN);
         else
                 pr_warning("MityOMAPL138: Invalid MAC found "
                                 "in factory config block\n");
+
+        partnum = factory_config.partnum;
+        pr_info("MityOMAPL138: Part Number = %s\n", partnum);
+
+bad_config:
+        /* default maximum speed is valid for all platforms */
+        mityomapl138_cpufreq_init(partnum);
 }
 
 static struct at24_platform_data mityomapl138_fd_chip = {
@@ -383,10 +454,6 @@ static void __init mityomapl138_init(void)
         if (ret)
                 pr_warning("rtc setup failed: %d\n", ret);
 
-        ret = da850_register_cpufreq("pll0_sysclk3");
-        if (ret)
-                pr_warning("cpufreq registration failed: %d\n", ret);
-
         ret = da8xx_register_cpuidle();
         if (ret)
                 pr_warning("cpuidle registration failed: %d\n", ret);