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Kernel: Implement Changing Bus Width per the SDHC specification

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Namely, we previously forgot to configure the SD Host Controller for
4-bit mode after issuing ACMD6, which caused data transfers to fail on
bare metal.
This commit is contained in:
Daniel Bertalan 2023-06-24 09:58:03 +02:00 committed by Jelle Raaijmakers
parent 73228fc742
commit bbe614c6c5
Notes: sideshowbarker 2024-07-17 03:19:14 +09:00 
Author: https://github.com/BertalanD
Commit: https://github.com/SerenityOS/serenity/commit/bbe614c6c5
Pull-request: https://github.com/SerenityOS/serenity/pull/19598
Reviewed-by: https://github.com/gmta ✅
Reviewed-by: https://github.com/supercomputer7 ✅
1 changed files with 15 additions and 0 deletions
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15
Kernel/Devices/Storage/SD/SDHostController.cpp
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@ -35,6 +35,7 @@ constexpr u32 max_supported_sdsc_frequency_high_speed = 50000000;
// In "m_registers->host_configuration_0"
// 2.2.11 Host Control 1 Register
constexpr u32 data_transfer_width_4bit = 1 << 1;
constexpr u32 high_speed_enable = 1 << 2;
constexpr u32 dma_select_adma2_32 = 0b10 << 3;
constexpr u32 dma_select_adma2_64 = 0b11 << 3;
@ -54,6 +55,7 @@ constexpr u32 command_complete = 1 << 0;
constexpr u32 transfer_complete = 1 << 1;
constexpr u32 buffer_write_ready = 1 << 4;
constexpr u32 buffer_read_ready = 1 << 5;
constexpr u32 card_interrupt = 1 << 8;
// PLSS 5.1: all voltage windows
constexpr u32 acmd41_voltage = 0x00ff8000;
@ -243,10 +245,23 @@ ErrorOr<NonnullLockRefPtr<SDMemoryCard>> SDHostController::try_initialize_insert
auto scr = TRY(retrieve_sd_configuration_register(rca));
// SDHC 3.4: "Changing Bus Width"
// 1. Set Card Interrupt Status Enable in the Normal Interrupt Status Enable register to 0 for
// masking incorrect interrupts that may occur while changing the bus width.
m_registers->interrupt_status_enable &= ~card_interrupt;
// 2. In case of SD memory only card, go to step (4). In case of other card, go to step (3).
// 4. Change the bus width mode for an SD card. SD Memory Card bus width is changed by ACMD6
// and SDIO card bus width is changed by setting Bus Width of Bus Interface Control register in
// CCCR.
TRY(issue_command(SD::Commands::app_cmd, rca));
TRY(wait_for_response());
TRY(issue_command(SD::Commands::app_set_bus_width, 0x2)); // 0b00=1 bit bus, 0b10=4 bit bus
TRY(wait_for_response());
// 5. In case of changing to 4-bit mode, set Data Transfer Width to 1 in the Host Control 1 register.
// In another case (1-bit mode), set this bit to 0.
m_registers->host_configuration_0 |= data_transfer_width_4bit;
// 6. In case of SD memory only card, go to the 'End'. In case of other card, go to step (7).
return TRY(DeviceManagement::try_create_device<SDMemoryCard>(
*this,