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From b14e4255f43ccf38b4f9df8f5793c9c4098e0ab9 Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Mon, 4 Apr 2016 16:03:18 +0100
Subject: [PATCH 225/381] bcm2835-sdhost: Firmware manages the clock divisor
The bcm2835-sdhost driver hands control of the CDIV clock divisor
register to matching firmware, allowing it to adjust to a changing
core clock. This removes the need to use the performance governor or
to enable io_is_busy on the on-demand governor in order to get the
best SD performance.
N.B. As SD clocks must be an integer divisor of the core clock, it is
possible that the SD clock for "turbo" mode can be different (even
lower) than "normal" mode.
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
---
drivers/mmc/host/bcm2835-sdhost.c | 120 ++++++++++++++++++-----------
include/soc/bcm2835/raspberrypi-firmware.h | 1 +
2 files changed, 74 insertions(+), 47 deletions(-)
--- a/drivers/mmc/host/bcm2835-sdhost.c
+++ b/drivers/mmc/host/bcm2835-sdhost.c
@@ -50,6 +50,7 @@
#include <linux/of_dma.h>
#include <linux/time.h>
#include <linux/workqueue.h>
+#include <soc/bcm2835/raspberrypi-firmware.h>
#define DRIVER_NAME "sdhost-bcm2835"
@@ -183,6 +184,7 @@ struct bcm2835_host {
unsigned int use_sbc:1; /* Send CMD23 */
unsigned int debug:1; /* Enable debug output */
+ unsigned int firmware_sets_cdiv:1; /* Let the firmware manage the clock */
/*DMA part*/
struct dma_chan *dma_chan_rxtx; /* DMA channel for reads and writes */
@@ -430,7 +432,7 @@ static void bcm2835_sdhost_reset_interna
host->clock = 0;
host->sectors = 0;
bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
- bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+ bcm2835_sdhost_write(host, SDCDIV_MAX_CDIV, SDCDIV);
mmiowb();
}
@@ -1534,62 +1536,75 @@ void bcm2835_sdhost_set_clock(struct bcm
host->mmc->actual_clock = 0;
- if (clock < 100000) {
- /* Can't stop the clock, but make it as slow as possible
- * to show willing
- */
- host->cdiv = SDCDIV_MAX_CDIV;
- bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
- return;
- }
-
- div = host->max_clk / clock;
- if (div < 2)
- div = 2;
- if ((host->max_clk / div) > clock)
- div++;
- div -= 2;
+ if (host->firmware_sets_cdiv) {
+ u32 msg[3] = { clock, 0, 0 };
- if (div > SDCDIV_MAX_CDIV)
- div = SDCDIV_MAX_CDIV;
+ rpi_firmware_property(rpi_firmware_get(NULL),
+ RPI_FIRMWARE_SET_SDHOST_CLOCK,
+ &msg, sizeof(msg));
- clock = host->max_clk / (div + 2);
- host->mmc->actual_clock = clock;
+ clock = max(msg[1], msg[2]);
+ } else {
+ if (clock < 100000) {
+ /* Can't stop the clock, but make it as slow as
+ * possible to show willing
+ */
+ host->cdiv = SDCDIV_MAX_CDIV;
+ bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+ return;
+ }
+
+ 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;
+
+ clock = host->max_clk / (div + 2);
+
+ host->cdiv = div;
+ bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
+
+ if (host->debug)
+ pr_info("%s: clock=%d -> max_clk=%d, cdiv=%x "
+ "(actual clock %d)\n",
+ mmc_hostname(host->mmc), input_clock,
+ host->max_clk, host->cdiv,
+ clock);
+ }
/* Calibrate some delays */
host->ns_per_fifo_word = (1000000000/clock) *
((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
- if (clock > input_clock) {
- /* Save the closest value, to make it easier
- to reduce in the event of error */
- host->overclock_50 = (clock/MHZ);
-
- if (clock != host->overclock) {
- pr_warn("%s: overclocking to %dHz\n",
- mmc_hostname(host->mmc), clock);
- host->overclock = clock;
+ if (input_clock == 50 * MHZ) {
+ if (clock > input_clock) {
+ /* Save the closest value, to make it easier
+ to reduce in the event of error */
+ host->overclock_50 = (clock/MHZ);
+
+ if (clock != host->overclock) {
+ pr_warn("%s: overclocking to %dHz\n",
+ mmc_hostname(host->mmc), clock);
+ host->overclock = clock;
+ }
+ } else if (host->overclock) {
+ host->overclock = 0;
+ if (clock == 50 * MHZ)
+ pr_warn("%s: cancelling overclock\n",
+ mmc_hostname(host->mmc));
}
}
- else if (host->overclock)
- {
- host->overclock = 0;
- if (clock == 50 * MHZ)
- pr_warn("%s: cancelling overclock\n",
- mmc_hostname(host->mmc));
- }
-
- host->cdiv = div;
- bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
/* Set the timeout to 500ms */
- bcm2835_sdhost_write(host, host->mmc->actual_clock/2, SDTOUT);
+ bcm2835_sdhost_write(host, clock/2, SDTOUT);
- if (host->debug)
- pr_info("%s: clock=%d -> max_clk=%d, cdiv=%x (actual clock %d)\n",
- mmc_hostname(host->mmc), input_clock,
- host->max_clk, host->cdiv, host->mmc->actual_clock);
+ host->mmc->actual_clock = clock;
}
static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
@@ -1704,11 +1719,6 @@ static void bcm2835_sdhost_set_ios(struc
log_event("IOS<", ios->clock, 0);
- if (!ios->clock || ios->clock != host->clock) {
- bcm2835_sdhost_set_clock(host, ios->clock);
- host->clock = ios->clock;
- }
-
/* set bus width */
host->hcfg &= ~SDHCFG_WIDE_EXT_BUS;
if (ios->bus_width == MMC_BUS_WIDTH_4)
@@ -1721,6 +1731,11 @@ static void bcm2835_sdhost_set_ios(struc
bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
+ if (!ios->clock || ios->clock != host->clock) {
+ bcm2835_sdhost_set_clock(host, ios->clock);
+ host->clock = ios->clock;
+ }
+
mmiowb();
spin_unlock_irqrestore(&host->lock, flags);
@@ -1953,6 +1968,7 @@ static int bcm2835_sdhost_probe(struct p
struct bcm2835_host *host;
struct mmc_host *mmc;
const __be32 *addr;
+ u32 msg[3];
int ret;
pr_debug("bcm2835_sdhost_probe\n");
@@ -2058,6 +2074,16 @@ static int bcm2835_sdhost_probe(struct p
else
mmc->caps |= MMC_CAP_4_BIT_DATA;
+ msg[0] = 0;
+ msg[1] = ~0;
+ msg[2] = ~0;
+
+ rpi_firmware_property(rpi_firmware_get(NULL),
+ RPI_FIRMWARE_SET_SDHOST_CLOCK,
+ &msg, sizeof(msg));
+
+ host->firmware_sets_cdiv = (msg[1] != ~0);
+
ret = bcm2835_sdhost_add_host(host);
if (ret)
goto err;
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -79,6 +79,7 @@ enum rpi_firmware_property_tag {
RPI_FIRMWARE_SET_VOLTAGE = 0x00038003,
RPI_FIRMWARE_SET_TURBO = 0x00038009,
RPI_FIRMWARE_SET_CUSTOMER_OTP = 0x00038021,
+ RPI_FIRMWARE_SET_SDHOST_CLOCK = 0x00038042,
/* Dispmanx TAGS */
RPI_FIRMWARE_FRAMEBUFFER_ALLOCATE = 0x00040001,
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