summaryrefslogtreecommitdiff
path: root/drivers/mmc
diff options
context:
space:
mode:
authorUlf Hansson <ulf.hansson@linaro.org>2024-09-13 18:28:16 +0800
committerUlf Hansson <ulf.hansson@linaro.org>2024-10-14 12:40:10 +0200
commit79daeb241db7901e4bd53cce9ab046f376a63a4c (patch)
tree803e5e6f3e0b1c322da4ca63b37e61173f0a605a /drivers/mmc
parentb948d7c57b8bcfff6a94fd5d0d2d615d2a947687 (diff)
mmc: core: Prepare to support SD UHS-II cards
The SD UHS-II interface was introduced to the SD spec v4.00 several years ago. The interface is fundamentally different from an electrical and a protocol point of view, comparing to the legacy SD interface. However, the legacy SD protocol is supported through a specific transport layer (SD-TRAN) defined in the UHS-II addendum of the spec. This allows the SD card to be managed in a very similar way as a legacy SD card, hence a lot of code can be re-used to support these new types of cards through the mmc subsystem. Moreover, an SD card that supports the UHS-II interface shall also be backwards compatible with the legacy SD interface, which allows a UHS-II card to be inserted into a legacy slot. As a matter of fact, this is already supported by mmc subsystem as of today. To prepare to add support for UHS-II, this change puts the basic foundation in the mmc core in place, allowing it to be more easily reviewed before subsequent changes implements the actual support. Basically, the approach here adds a new UHS-II bus_ops type and adds a separate initialization path for the UHS-II card. The intent is to avoid us from sprinkling the legacy initialization path, but also to simplify implementation of the UHS-II specific bits. At this point, there is only one new host ops added to manage the various ios settings needed for UHS-II. Additional host ops that are needed, are being added from subsequent changes. Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Link: https://lore.kernel.org/r/20240913102836.6144-3-victorshihgli@gmail.com
Diffstat (limited to 'drivers/mmc')
-rw-r--r--drivers/mmc/core/Makefile2
-rw-r--r--drivers/mmc/core/core.c17
-rw-r--r--drivers/mmc/core/core.h1
-rw-r--r--drivers/mmc/core/sd_uhs2.c294
4 files changed, 312 insertions, 2 deletions
diff --git a/drivers/mmc/core/Makefile b/drivers/mmc/core/Makefile
index 6a907736cd7a..15b067e8b0d1 100644
--- a/drivers/mmc/core/Makefile
+++ b/drivers/mmc/core/Makefile
@@ -7,7 +7,7 @@ obj-$(CONFIG_MMC) += mmc_core.o
mmc_core-y := core.o bus.o host.o \
mmc.o mmc_ops.o sd.o sd_ops.o \
sdio.o sdio_ops.o sdio_bus.o \
- sdio_cis.o sdio_io.o sdio_irq.o \
+ sdio_cis.o sdio_io.o sdio_irq.o sd_uhs2.o\
slot-gpio.o regulator.o
mmc_core-$(CONFIG_OF) += pwrseq.o
obj-$(CONFIG_PWRSEQ_SIMPLE) += pwrseq_simple.o
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 01a7142eada3..54ca9dc2114c 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2267,6 +2267,18 @@ void mmc_rescan(struct work_struct *work)
goto out;
}
+ /*
+ * Ideally we should favor initialization of legacy SD cards and defer
+ * UHS-II enumeration. However, it seems like cards doesn't reliably
+ * announce their support for UHS-II in the response to the ACMD41,
+ * while initializing the legacy SD interface. Therefore, let's start
+ * with UHS-II for now.
+ */
+ if (!mmc_attach_sd_uhs2(host)) {
+ mmc_release_host(host);
+ goto out;
+ }
+
for (i = 0; i < ARRAY_SIZE(freqs); i++) {
unsigned int freq = freqs[i];
if (freq > host->f_max) {
@@ -2299,10 +2311,13 @@ void mmc_rescan(struct work_struct *work)
void mmc_start_host(struct mmc_host *host)
{
+ bool power_up = !(host->caps2 &
+ (MMC_CAP2_NO_PRESCAN_POWERUP | MMC_CAP2_SD_UHS2));
+
host->f_init = max(min(freqs[0], host->f_max), host->f_min);
host->rescan_disable = 0;
- if (!(host->caps2 & MMC_CAP2_NO_PRESCAN_POWERUP)) {
+ if (power_up) {
mmc_claim_host(host);
mmc_power_up(host, host->ocr_avail);
mmc_release_host(host);
diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
index fc9d5e9620b1..fc9c066e6468 100644
--- a/drivers/mmc/core/core.h
+++ b/drivers/mmc/core/core.h
@@ -81,6 +81,7 @@ int mmc_detect_card_removed(struct mmc_host *host);
int mmc_attach_mmc(struct mmc_host *host);
int mmc_attach_sd(struct mmc_host *host);
int mmc_attach_sdio(struct mmc_host *host);
+int mmc_attach_sd_uhs2(struct mmc_host *host);
/* Module parameters */
extern bool use_spi_crc;
diff --git a/drivers/mmc/core/sd_uhs2.c b/drivers/mmc/core/sd_uhs2.c
new file mode 100644
index 000000000000..19d62d45e1ec
--- /dev/null
+++ b/drivers/mmc/core/sd_uhs2.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2021 Linaro Ltd
+ *
+ * Author: Ulf Hansson <ulf.hansson@linaro.org>
+ *
+ * Support for SD UHS-II cards
+ */
+#include <linux/err.h>
+
+#include <linux/mmc/host.h>
+#include <linux/mmc/card.h>
+
+#include "core.h"
+#include "bus.h"
+#include "sd.h"
+#include "mmc_ops.h"
+
+static const unsigned int sd_uhs2_freqs[] = { 52000000, 26000000 };
+
+static int sd_uhs2_power_up(struct mmc_host *host)
+{
+ int err;
+
+ if (host->ios.power_mode == MMC_POWER_ON)
+ return 0;
+
+ host->ios.vdd = fls(host->ocr_avail) - 1;
+ host->ios.clock = host->f_init;
+ host->ios.timing = MMC_TIMING_UHS2_SPEED_A;
+ host->ios.power_mode = MMC_POWER_ON;
+
+ err = host->ops->uhs2_control(host, UHS2_SET_IOS);
+
+ return err;
+}
+
+static int sd_uhs2_power_off(struct mmc_host *host)
+{
+ if (host->ios.power_mode == MMC_POWER_OFF)
+ return 0;
+
+ host->ios.vdd = 0;
+ host->ios.clock = 0;
+ host->ios.timing = MMC_TIMING_LEGACY;
+ host->ios.power_mode = MMC_POWER_OFF;
+
+ return host->ops->uhs2_control(host, UHS2_SET_IOS);
+}
+
+/*
+ * Run the phy initialization sequence, which mainly relies on the UHS-II host
+ * to check that we reach the expected electrical state, between the host and
+ * the card.
+ */
+static int sd_uhs2_phy_init(struct mmc_host *host)
+{
+ return 0;
+}
+
+/*
+ * Do the early initialization of the card, by sending the device init broadcast
+ * command and wait for the process to be completed.
+ */
+static int sd_uhs2_dev_init(struct mmc_host *host)
+{
+ return 0;
+}
+
+/*
+ * Run the enumeration process by sending the enumerate command to the card.
+ * Note that, we currently support only the point to point connection, which
+ * means only one card can be attached per host/slot.
+ */
+static int sd_uhs2_enum(struct mmc_host *host, u32 *node_id)
+{
+ return 0;
+}
+
+/*
+ * Read the UHS-II configuration registers (CFG_REG) of the card, by sending it
+ * commands and by parsing the responses. Store a copy of the relevant data in
+ * card->uhs2_config.
+ */
+static int sd_uhs2_config_read(struct mmc_host *host, struct mmc_card *card)
+{
+ return 0;
+}
+
+/*
+ * Based on the card's and host's UHS-II capabilities, let's update the
+ * configuration of the card and the host. This may also include to move to a
+ * greater speed range/mode. Depending on the updated configuration, we may need
+ * to do a soft reset of the card via sending it a GO_DORMANT_STATE command.
+ *
+ * In the final step, let's check if the card signals "config completion", which
+ * indicates that the card has moved from config state into active state.
+ */
+static int sd_uhs2_config_write(struct mmc_host *host, struct mmc_card *card)
+{
+ return 0;
+}
+
+/*
+ * Initialize the UHS-II card through the SD-TRAN transport layer. This enables
+ * commands/requests to be backwards compatible through the legacy SD protocol.
+ * UHS-II cards has a specific power limit specified for VDD1/VDD2, that should
+ * be set through a legacy CMD6. Note that, the power limit that becomes set,
+ * survives a soft reset through the GO_DORMANT_STATE command.
+ */
+static int sd_uhs2_legacy_init(struct mmc_host *host, struct mmc_card *card)
+{
+ return 0;
+}
+
+/*
+ * Allocate the data structure for the mmc_card and run the UHS-II specific
+ * initialization sequence.
+ */
+static int sd_uhs2_init_card(struct mmc_host *host)
+{
+ struct mmc_card *card;
+ u32 node_id = 0;
+ int err;
+
+ err = sd_uhs2_dev_init(host);
+ if (err)
+ return err;
+
+ err = sd_uhs2_enum(host, &node_id);
+ if (err)
+ return err;
+
+ card = mmc_alloc_card(host, &sd_type);
+ if (IS_ERR(card))
+ return PTR_ERR(card);
+
+ card->uhs2_config.node_id = node_id;
+ card->type = MMC_TYPE_SD;
+
+ err = sd_uhs2_config_read(host, card);
+ if (err)
+ goto err;
+
+ err = sd_uhs2_config_write(host, card);
+ if (err)
+ goto err;
+
+ host->card = card;
+ return 0;
+
+err:
+ mmc_remove_card(card);
+ return err;
+}
+
+static void sd_uhs2_remove(struct mmc_host *host)
+{
+ mmc_remove_card(host->card);
+ host->card = NULL;
+}
+
+static int sd_uhs2_alive(struct mmc_host *host)
+{
+ return mmc_send_status(host->card, NULL);
+}
+
+static void sd_uhs2_detect(struct mmc_host *host)
+{
+ int err;
+
+ mmc_get_card(host->card, NULL);
+ err = _mmc_detect_card_removed(host);
+ mmc_put_card(host->card, NULL);
+
+ if (err) {
+ sd_uhs2_remove(host);
+
+ mmc_claim_host(host);
+ mmc_detach_bus(host);
+ sd_uhs2_power_off(host);
+ mmc_release_host(host);
+ }
+}
+
+static int sd_uhs2_suspend(struct mmc_host *host)
+{
+ return 0;
+}
+
+static int sd_uhs2_resume(struct mmc_host *host)
+{
+ return 0;
+}
+
+static int sd_uhs2_runtime_suspend(struct mmc_host *host)
+{
+ return 0;
+}
+
+static int sd_uhs2_runtime_resume(struct mmc_host *host)
+{
+ return 0;
+}
+
+static int sd_uhs2_shutdown(struct mmc_host *host)
+{
+ return 0;
+}
+
+static int sd_uhs2_hw_reset(struct mmc_host *host)
+{
+ return 0;
+}
+
+static const struct mmc_bus_ops sd_uhs2_ops = {
+ .remove = sd_uhs2_remove,
+ .alive = sd_uhs2_alive,
+ .detect = sd_uhs2_detect,
+ .suspend = sd_uhs2_suspend,
+ .resume = sd_uhs2_resume,
+ .runtime_suspend = sd_uhs2_runtime_suspend,
+ .runtime_resume = sd_uhs2_runtime_resume,
+ .shutdown = sd_uhs2_shutdown,
+ .hw_reset = sd_uhs2_hw_reset,
+};
+
+static int sd_uhs2_attach(struct mmc_host *host)
+{
+ int err;
+
+ err = sd_uhs2_power_up(host);
+ if (err)
+ goto err;
+
+ err = sd_uhs2_phy_init(host);
+ if (err)
+ goto err;
+
+ err = sd_uhs2_init_card(host);
+ if (err)
+ goto err;
+
+ err = sd_uhs2_legacy_init(host, host->card);
+ if (err)
+ goto err;
+
+ mmc_attach_bus(host, &sd_uhs2_ops);
+
+ mmc_release_host(host);
+
+ err = mmc_add_card(host->card);
+ if (err)
+ goto remove_card;
+
+ mmc_claim_host(host);
+ return 0;
+
+remove_card:
+ mmc_remove_card(host->card);
+ host->card = NULL;
+ mmc_claim_host(host);
+ mmc_detach_bus(host);
+err:
+ sd_uhs2_power_off(host);
+ return err;
+}
+
+int mmc_attach_sd_uhs2(struct mmc_host *host)
+{
+ int i, err = 0;
+
+ if (!(host->caps2 & MMC_CAP2_SD_UHS2))
+ return -EOPNOTSUPP;
+
+ /* Turn off the legacy SD interface before trying with UHS-II. */
+ mmc_power_off(host);
+
+ /*
+ * Start UHS-II initialization at 52MHz and possibly make a retry at
+ * 26MHz according to the spec. It's required that the host driver
+ * validates ios->clock, to set a rate within the correct range.
+ */
+ for (i = 0; i < ARRAY_SIZE(sd_uhs2_freqs); i++) {
+ host->f_init = sd_uhs2_freqs[i];
+ pr_debug("%s: %s: trying to init UHS-II card at %u Hz\n",
+ mmc_hostname(host), __func__, host->f_init);
+ err = sd_uhs2_attach(host);
+ if (!err)
+ break;
+ }
+
+ return err;
+}