From 3d705d14fe4c72be83bae1610680e209ee226b9d Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Tue, 19 Aug 2014 10:45:51 +0200 Subject: mmc: implement Driver Stage Register handling MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Some eMMC and SD cards implement a DSR register that allows to tune raise/fall times and drive strength of the CMD and DATA outputs. The values to use depend on the card in use and the host. It might be needed to reduce the drive strength to prevent voltage peaks above the host's specification. Implement a 'dsr' devicetree property that allows to specify the value to set the DSR to. For non-dt setups the new members of mmc_host can be set by board code. This patch was initially authored by Sascha Hauer. It contains improvements authored by Markus Niebel and Uwe Kleine-König. Signed-off-by: Sascha Hauer Signed-off-by: Markus Niebel Signed-off-by: Uwe Kleine-König Signed-off-by: Ulf Hansson --- include/linux/mmc/card.h | 3 ++- include/linux/mmc/host.h | 3 +++ 2 files changed, 5 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h index bde5147a4221..0ea795f5feb9 100644 --- a/include/linux/mmc/card.h +++ b/include/linux/mmc/card.h @@ -42,7 +42,8 @@ struct mmc_csd { unsigned int read_partial:1, read_misalign:1, write_partial:1, - write_misalign:1; + write_misalign:1, + dsr_imp:1; }; struct mmc_ext_csd { diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index 7960424d0bc0..4cbf61476999 100644 --- a/include/linux/mmc/host.h +++ b/include/linux/mmc/host.h @@ -365,6 +365,9 @@ struct mmc_host { unsigned int slotno; /* used for sdio acpi binding */ + int dsr_req; /* DSR value is valid */ + u32 dsr; /* optional driver stage (DSR) value */ + unsigned long private[0] ____cacheline_aligned; }; -- cgit v1.2.3