From 22d4dc31f8ad093bc614a053fd8291d307ddc181 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Sat, 1 Jul 2017 18:43:58 +0200
Subject: [PATCH] flash_sdcard: add flash_sdcard_size to get SD card size

---
 lib/flash_sdcard.c | 35 +++++++++++++++++++++++++++++++----
 lib/flash_sdcard.h |  4 ++++
 2 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/lib/flash_sdcard.c b/lib/flash_sdcard.c
index 14106ae..6c55a3b 100644
--- a/lib/flash_sdcard.c
+++ b/lib/flash_sdcard.c
@@ -19,6 +19,7 @@
  *  @note peripherals used: SPI @ref flash_sdcard_spi
  *  @warning all calls are blocking
  *  @implements SD Specifications, Part 1, Physical Layer, Simplified Specification, Version 6.00, 10 April 10 2017
+ *  @todo use SPI unidirectional mode and DMA
  */
 
 /* standard libraries */
@@ -40,7 +41,9 @@
 #define FLASH_SDCARD_SPI 1 /**< SPI peripheral */
 /** @} */
 
-/** maximum N_AC value (time between the response token R1 and data block when reading data (see section 7.5.4)
+/** if the card has been initialized successfully */
+static bool initialized = false;
+/** maximum N_AC value (in 8-clock cycles) (time between the response token R1 and data block when reading data (see section 7.5.4)
  *  @note this is set to N_CR until we can read CSD (see section 7.2.6)
  */
 static uint32_t n_ac = 8;
@@ -49,6 +52,8 @@ static uint32_t n_ac = 8;
  *  @note this is important for addressing: for standard capacity cards the address is the byte number, for high capacity cards it is the 512-byte block number
  */
 static bool sdsc = false;
+/** size of card in bytes */
+static uint64_t sdcard_size = 0;
 
 /** table for CRC-7 calculation for the command messages (see section 4.5)
  *  @note faster than calculating the CRC and doesn't cost a lot of space
@@ -222,6 +227,11 @@ static uint8_t flash_sdcard_data_read(uint8_t index, uint32_t argument, uint8_t*
 
 bool flash_sdcard_setup(void)
 {
+	// reset values
+	initialized = false;
+	n_ac = 8;
+	sdcard_size = 0;
+
 	// check if card is present
 	if (!flash_sdcard_card_detect()) {
 		return false;
@@ -314,10 +324,10 @@ bool flash_sdcard_setup(void)
 		return false;
 	}
 	// check if CSD structure version matches capacity (see section 5.3.1)
-	if ((sdsc && (csd[0]&0xc0)) || (!sdsc && 0x40!=(csd[0]&0xc0))) {
+	if ((sdsc && (csd[0]>>6)) || (!sdsc && 0==(csd[0]>>6))) {
 		return false;
 	}
-	// we use our set minimum frequency 16 MHz to calculate time
+	// calculate N_AC value (we use our set minimum frequency 16 MHz to calculate time)
 	if (sdsc) { // calculate N_AC using TAAC and NSAC
 		static const float TAAC_UNITS[] = {1E-9, 10E-9, 100E-9, 1E-6, 10E-6, 100E-6, 1E-3, 10E-3}; // (see table 5-5)
 		static const float TAAC_VALUES[] = {10.0, 1.0, 1.2, 1.3, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 7.0, 8.0}; // (see table 5-5)
@@ -326,6 +336,16 @@ bool flash_sdcard_setup(void)
 	} else { // value is fixed to 100 ms
 		n_ac=100E-3*16E6/8;
 	}
+	// calculate size
+	if (sdsc) { // see section 5.3.2
+		uint16_t c_size = (((uint16_t)csd[6]&0x03)<<10)+((uint16_t)csd[7]<<2)+(csd[8]>>6);
+		uint8_t c_size_mutl = ((csd[9]&0x03)<<1)+((csd[10]&0x80)>>7);
+		uint8_t read_bl_len = (csd[5]&0x0f);
+		sdcard_size = ((c_size+1)*(1UL<<(c_size_mutl+2)))*(1UL<<read_bl_len);
+	} else { // see section 5.3.3
+		uint32_t c_size = ((uint32_t)(csd[7]&0x3f)<<16)+((uint16_t)csd[8]<<8)+csd[9];
+		sdcard_size = (c_size+1)*(512<<10);
+	}
 	
 	// ensure block length is 512 bytes for SDSC (should be per default) to we match SDHC/SDXC block size
 	if (sdsc) {
@@ -364,5 +384,12 @@ bool flash_sdcard_setup(void)
 		n_ac = n_ac_back; // restore N_AC
 	}
 
-	return true;
+	initialized = true;
+
+	return initialized;
+}
+
+uint64_t flash_sdcard_size(void)
+{
+	return sdcard_size;
 }
diff --git a/lib/flash_sdcard.h b/lib/flash_sdcard.h
index cee9ade..fce114f 100644
--- a/lib/flash_sdcard.h
+++ b/lib/flash_sdcard.h
@@ -25,3 +25,7 @@
  *  @return if card has been initialized correctly
  */
 bool flash_sdcard_setup(void);
+/** return size of SD card flash memory
+ *  @return size of SD card flash memory in bytes
+ */
+uint64_t flash_sdcard_size(void);