[SeaBIOS] [PATCH 2/5] sdcard: Implement controller frequency setting according to sdhci spec
Kevin O'Connor
kevin at koconnor.net
Fri Jul 31 00:36:20 CEST 2015
Signed-off-by: Kevin O'Connor <kevin at koconnor.net>
---
src/hw/sdcard.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 42 insertions(+), 2 deletions(-)
diff --git a/src/hw/sdcard.c b/src/hw/sdcard.c
index 7523ab8..57f44b0 100644
--- a/src/hw/sdcard.c
+++ b/src/hw/sdcard.c
@@ -43,7 +43,7 @@ struct sdhci_s {
u16 error_signal;
u16 auto_cmd12;
u8 pad_3E[2];
- u64 cap;
+ u32 cap_lo, cap_hi;
u64 max_current;
u16 force_auto_cmd12;
u16 force_error;
@@ -83,6 +83,16 @@ struct sdhci_s {
#define ST_READ (1<<4)
#define ST_MULTIPLE (1<<5)
+// SDHCI capabilities flags
+#define SD_CAPLO_BASECLOCK_SHIFT 8
+#define SD_CAPLO_BASECLOCK_MASK 0x3f
+
+// SDHCI clock control flags
+#define SCC_INTERNAL_ENABLE (1<<0)
+#define SCC_STABLE (1<<1)
+#define SCC_CLOCK_ENABLE (1<<2)
+#define SCC_SDCLK_SHIFT 8
+
// SDHCI result flags
#define SR_OCR_CCS (1<<30)
@@ -255,6 +265,31 @@ sdcard_card_setup(struct sdhci_s *regs)
return card_type;
}
+static int
+sdcard_set_frequency(struct sdhci_s *regs, u32 khz)
+{
+ u32 cap = readl(®s->cap_lo);
+ u32 base_freq = (cap >> SD_CAPLO_BASECLOCK_SHIFT) & SD_CAPLO_BASECLOCK_MASK;
+ if (!base_freq) {
+ dprintf(1, "Unknown base frequency for SD controller\n");
+ return -1;
+ }
+ // Set new frequency
+ u32 divisor = DIV_ROUND_UP(base_freq * 1000, khz);
+ divisor = divisor >= 1 ? 1 << (__ffs(divisor-1)+1) : 0;
+ u16 creg = (divisor << SCC_SDCLK_SHIFT) | SCC_INTERNAL_ENABLE;
+ writew(®s->clock_control, 0);
+ writew(®s->clock_control, creg);
+ // Wait for frequency to become active
+ u32 end = timer_calc(SDHCI_PIO_TIMEOUT);
+ int ret = waitw((u16*)®s->clock_control, SCC_STABLE, SCC_STABLE, end);
+ if (ret)
+ return ret;
+ // Enable SD clock
+ writew(®s->clock_control, creg | SCC_CLOCK_ENABLE);
+ return 0;
+}
+
// Setup and configure an SD card controller
static void
sdcard_controller_setup(void *data)
@@ -277,13 +312,18 @@ sdcard_controller_setup(void *data)
writew(®s->irq_signal, 0);
writew(®s->irq_enable, 0xffff);
writew(®s->error_signal, 0);
+ int ret = sdcard_set_frequency(regs, 400);
+ if (ret)
+ return;
writeb(®s->power_control, 0x0f);
- writew(®s->clock_control, 0x0005);
// Initialize card
int card_type = sdcard_card_setup(regs);
if (card_type < 0)
return;
+ ret = sdcard_set_frequency(regs, 25000);
+ if (ret)
+ return;
// Register drive
struct sddrive_s *drive = malloc_fseg(sizeof(*drive));
--
1.9.3
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