From f3a870bfa075fb880f5e018a0a5ae6f27ca8be49 Mon Sep 17 00:00:00 2001
From: Vincent Fazio <vfazio@xes-inc.com>
Date: Mon, 13 Sep 2021 13:34:45 -0500
Subject: [PATCH] mmc: bcm2835-host: let firmware manage the clock
Newer firmware supports managing the sdhost clock divisor, so leverage
this feature if it is available.
SET_SDHOST_CLOCK is largely undocumented except for its usage within the
Linux kernel, which this change is based on.
https://github.com/raspberrypi/linux/commit/3cd16c39c718e2dda7885c4ed7a20118aed12524
Signed-off-by: Vincent Fazio <vfazio@xes-inc.com>
---
arch/arm/mach-bcm283x/include/mach/mbox.h | 18 ++++++++
arch/arm/mach-bcm283x/include/mach/msg.h | 10 +++++
arch/arm/mach-bcm283x/msg.c | 30 +++++++++++++
drivers/mmc/bcm2835_sdhost.c | 53 ++++++++++++++---------
4 files changed, 90 insertions(+), 21 deletions(-)
diff --git a/arch/arm/mach-bcm283x/include/mach/mbox.h b/arch/arm/mach-bcm283x/include/mach/mbox.h
index 7dcac583cc4..9b1943fcfc4 100644
--- a/arch/arm/mach-bcm283x/include/mach/mbox.h
+++ b/arch/arm/mach-bcm283x/include/mach/mbox.h
@@ -252,6 +252,24 @@ struct bcm2835_mbox_tag_get_clock_rate {
} body;
};
+#define BCM2835_MBOX_TAG_SET_SDHOST_CLOCK 0x00038042
+
+struct bcm2835_mbox_tag_set_sdhost_clock {
+ struct bcm2835_mbox_tag_hdr tag_hdr;
+ union {
+ struct {
+ u32 rate_hz;
+ u32 rate_1;
+ u32 rate_2;
+ } req;
+ struct {
+ u32 rate_hz;
+ u32 rate_1;
+ u32 rate_2;
+ } resp;
+ } body;
+};
+
#define BCM2835_MBOX_TAG_ALLOCATE_BUFFER 0x00040001
struct bcm2835_mbox_tag_allocate_buffer {
diff --git a/arch/arm/mach-bcm283x/include/mach/msg.h b/arch/arm/mach-bcm283x/include/mach/msg.h
index e45c1bf010f..ab37abdb6c6 100644
--- a/arch/arm/mach-bcm283x/include/mach/msg.h
+++ b/arch/arm/mach-bcm283x/include/mach/msg.h
@@ -22,6 +22,16 @@ int bcm2835_power_on_module(u32 module);
*/
int bcm2835_get_mmc_clock(u32 clock_id);
+/**
+ * bcm2835_set_sdhost_clock() - determine if firmware controls sdhost cdiv
+ *
+ * @rate_hz: Input clock frequency
+ * @rate_1: Returns a clock frequency
+ * @rate_2: Returns a clock frequency
+ * @return 0 of OK, -EIO on error
+ */
+int bcm2835_set_sdhost_clock(u32 rate_hz, u32 *rate_1, u32 *rate_2);
+
/**
* bcm2835_get_video_size() - get the current display size
*
diff --git a/arch/arm/mach-bcm283x/msg.c b/arch/arm/mach-bcm283x/msg.c
index e2badfecb09..8c1c36a5f15 100644
--- a/arch/arm/mach-bcm283x/msg.c
+++ b/arch/arm/mach-bcm283x/msg.c
@@ -21,6 +21,12 @@ struct msg_get_clock_rate {
u32 end_tag;
};
+struct msg_set_sdhost_clock {
+ struct bcm2835_mbox_hdr hdr;
+ struct bcm2835_mbox_tag_set_sdhost_clock set_sdhost_clock;
+ u32 end_tag;
+};
+
struct msg_query {
struct bcm2835_mbox_hdr hdr;
struct bcm2835_mbox_tag_physical_w_h physical_w_h;
@@ -111,6 +117,30 @@ int bcm2835_get_mmc_clock(u32 clock_id)
return clock_rate;
}
+int bcm2835_set_sdhost_clock(u32 rate_hz, u32 *rate_1, u32 *rate_2)
+{
+ ALLOC_CACHE_ALIGN_BUFFER(struct msg_set_sdhost_clock, msg_sdhost_clk, 1);
+ int ret;
+
+ BCM2835_MBOX_INIT_HDR(msg_sdhost_clk);
+ BCM2835_MBOX_INIT_TAG(&msg_sdhost_clk->set_sdhost_clock, SET_SDHOST_CLOCK);
+
+ msg_sdhost_clk->set_sdhost_clock.body.req.rate_hz = rate_hz;
+ msg_sdhost_clk->set_sdhost_clock.body.req.rate_1 = *rate_1;
+ msg_sdhost_clk->set_sdhost_clock.body.req.rate_2 = *rate_2;
+
+ ret = bcm2835_mbox_call_prop(BCM2835_MBOX_PROP_CHAN, &msg_sdhost_clk->hdr);
+ if (ret) {
+ printf("bcm2835: Could not query sdhost clock rate\n");
+ return -EIO;
+ }
+
+ *rate_1 = msg_sdhost_clk->set_sdhost_clock.body.resp.rate_1;
+ *rate_2 = msg_sdhost_clk->set_sdhost_clock.body.resp.rate_2;
+
+ return 0;
+}
+
int bcm2835_get_video_size(int *widthp, int *heightp)
{
ALLOC_CACHE_ALIGN_BUFFER(struct msg_query, msg_query, 1);
diff --git a/drivers/mmc/bcm2835_sdhost.c b/drivers/mmc/bcm2835_sdhost.c
index 894dbdd6861..3a9cd6f1eb2 100644
--- a/drivers/mmc/bcm2835_sdhost.c
+++ b/drivers/mmc/bcm2835_sdhost.c
@@ -181,6 +181,7 @@ struct bcm2835_host {
struct udevice *dev;
struct mmc *mmc;
struct bcm2835_plat *plat;
+ unsigned int firmware_sets_cdiv:1;
};
static void bcm2835_dumpregs(struct bcm2835_host *host)
@@ -233,7 +234,7 @@ static void bcm2835_reset_internal(struct bcm2835_host *host)
msleep(20);
host->clock = 0;
writel(host->hcfg, host->ioaddr + SDHCFG);
- writel(host->cdiv, host->ioaddr + SDCDIV);
+ writel(SDCDIV_MAX_CDIV, host->ioaddr + SDCDIV);
}
static int bcm2835_wait_transfer_complete(struct bcm2835_host *host)
@@ -598,6 +599,7 @@ static int bcm2835_transmit(struct bcm2835_host *host)
static void bcm2835_set_clock(struct bcm2835_host *host, unsigned int clock)
{
int div;
+ u32 clock_rate[2] = { 0 };
/* The SDCDIV register has 11 bits, and holds (div - 2). But
* in data mode the max is 50MHz wihout a minimum, and only
@@ -620,26 +622,34 @@ static void bcm2835_set_clock(struct bcm2835_host *host, unsigned int clock)
* clock divisor at all times.
*/
- if (clock < 100000) {
- /* Can't stop the clock, but make it as slow as possible
- * to show willing
- */
- host->cdiv = SDCDIV_MAX_CDIV;
- writel(host->cdiv, host->ioaddr + SDCDIV);
- return;
- }
+ if (host->firmware_sets_cdiv) {
+ bcm2835_set_sdhost_clock(clock, &clock_rate[0], &clock_rate[1]);
+ clock = max(clock_rate[0], clock_rate[1]);
+ } else {
+ if (clock < 100000) {
+ /* Can't stop the clock, but make it as slow as possible
+ * to show willing
+ */
+ host->cdiv = SDCDIV_MAX_CDIV;
+ writel(host->cdiv, host->ioaddr + SDCDIV);
+ return;
+ }
- div = host->max_clk / clock;
- if (div < 2)
- div = 2;
- if ((host->max_clk / div) > clock)
- div++;
- div -= 2;
+ div = host->max_clk / clock;
+ if (div < 2)
+ div = 2;
+ if ((host->max_clk / div) > clock)
+ div++;
+ div -= 2;
- if (div > SDCDIV_MAX_CDIV)
- div = SDCDIV_MAX_CDIV;
+ if (div > SDCDIV_MAX_CDIV)
+ div = SDCDIV_MAX_CDIV;
+
+ clock = host->max_clk / (div + 2);
+ host->cdiv = div;
+ writel(host->cdiv, host->ioaddr + SDCDIV);
+ }
- clock = host->max_clk / (div + 2);
host->mmc->clock = clock;
/* Calibrate some delays */
@@ -647,9 +657,6 @@ static void bcm2835_set_clock(struct bcm2835_host *host, unsigned int clock)
host->ns_per_fifo_word = (1000000000 / clock) *
((host->mmc->card_caps & MMC_MODE_4BIT) ? 8 : 32);
- host->cdiv = div;
- writel(host->cdiv, host->ioaddr + SDCDIV);
-
/* Set the timeout to 500ms */
writel(host->mmc->clock / 2, host->ioaddr + SDTOUT);
}
@@ -759,6 +766,7 @@ static int bcm2835_probe(struct udevice *dev)
struct bcm2835_host *host = dev_get_priv(dev);
struct mmc *mmc = mmc_get_mmc_dev(dev);
struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
+ u32 clock_rate[2] = { ~0 };
host->dev = dev;
host->mmc = mmc;
@@ -776,6 +784,9 @@ static int bcm2835_probe(struct udevice *dev)
host->max_clk = bcm2835_get_mmc_clock(BCM2835_MBOX_CLOCK_ID_CORE);
+ bcm2835_set_sdhost_clock(0, &clock_rate[0], &clock_rate[1]);
+ host->firmware_sets_cdiv = (clock_rate[0] != ~0);
+
bcm2835_add_host(host);
dev_dbg(dev, "%s -> OK\n", __func__);