[U-Boot] [PATCH 1/2] arm: socfpga: mmc: Enable calibration for drvsel and smpsel

Chin Liang See
2015-08-19T05:54:50Z

Enable SDMMC calibration to determine the best setting for
drvsel and smpsel. It will be triggered whenever there is
a change of card frequency and bus width. This is to ensure
reliable transmission between the controller and the card.

Signed-off-by: Chin Liang See <clsee@altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Pavel Machek <pavel@denx.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Stefan Roese <sr@denx.de>
Cc: Tom Rini <trini@konsulko.com>
---
drivers/mmc/socfpga_dw_mmc.c | 187 ++++++++++++++++++++++++++++++++++++++++--
1 files changed, 180 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/socfpga_dw_mmc.c b/drivers/mmc/socfpga_dw_mmc.c
index eb69aed..15e537c 100644
--- a/drivers/mmc/socfpga_dw_mmc.c
+++ b/drivers/mmc/socfpga_dw_mmc.c
@@ -11,25 +11,140 @@
#include <asm/arch/dwmmc.h>
#include <asm/arch/clock_manager.h>
#include <asm/arch/system_manager.h>
+#include "mmc_private.h"

static const struct socfpga_clock_manager *clock_manager_base =
(void *)SOCFPGA_CLKMGR_ADDRESS;
static const struct socfpga_system_manager *system_manager_base =
(void *)SOCFPGA_SYSMGR_ADDRESS;

-static void socfpga_dwmci_clksel(struct dwmci_host *host)
+#define CAL_ROWS 7
+#define CAL_COLS 8
+
+/*
+ * This function determines the largest rectangle filled with 1's and returns
+ * the middle. This functon can be optimized, for example using the algorithm
+ * from http://www.drdobbs.com/database/the-maximal-rectangle-problem/184410529
+ * It currently takes less than 1ms, while creating the input data takes ~5ms
+ * so there is not a real need to optimize it.
+ */
+int find_calibration_point(unsigned char cal_results[CAL_ROWS][CAL_COLS],
+unsigned int sum, unsigned int * cal_row, unsigned int * cal_col)
{
- unsigned int drvsel;
- unsigned int smplsel;
+ /* Structure containing a rectangle candidate */
+ typedef struct
+ {
+ unsigned char height;
+ unsigned char width;
+ unsigned short area;
+ } rect_cand_t;
+
+ /* Array with the rectangle candidates */
+ rect_cand_t rect_cands[CAL_ROWS * CAL_COLS];
+ unsigned char cr_rect_cand = 0;
+ unsigned char height, width, k;
+
+ /* No solution if all combinations fail */
+ if(sum == 0)
+ return 1;
+
+ /* Simple solution if all combinations pass */
+ if(sum == (CAL_ROWS * CAL_COLS)) {
+ *cal_row = (CAL_ROWS - 1) / 2;
+ *cal_col = (CAL_COLS - 1) / 2;
+ return 0;
+ }
+
+ /*
+ * Create list of all possible sub-rectangles, in descending area
+ * order
+ */
+ for(height = CAL_ROWS; height >= 1; height--) {
+ for(width = CAL_COLS; width >= 1 ; width--){
+ /* Add a new rectangle candidate */
+ rect_cands[cr_rect_cand].height = height;
+ rect_cands[cr_rect_cand].width = width;
+ rect_cands[cr_rect_cand].area = height * width;
+ cr_rect_cand++;
+
+ /* First candidate it always in the right position */
+ if(cr_rect_cand == 1)
+ continue;
+
+ /*
+ * Put the candidate in right location to maintain
+ * descending order
+ */
+ for(k = cr_rect_cand - 1; k > 1; k--){
+ if(rect_cands[k-1].area < rect_cands[k].area){
+ rect_cand_t tmp = rect_cands[k-1];
+ rect_cands[k-1] = rect_cands[k];
+ rect_cands[k] = tmp;
+ } else
+ break;
+ }
+ }
+ }
+
+ /* Try to fit the rectangle candidates, in descending area order */
+ for(k = 0; k < CAL_ROWS * CAL_COLS; k++) {
+ unsigned char start_row, start_col;
+ unsigned rect_width = rect_cands[k].width;
+ unsigned rect_height = rect_cands[k].height;
+
+ /* Find the row and column where the candidate fits */
+ for (start_col = 0; start_col < (CAL_COLS - rect_width + 1);
+ start_col++) {
+ for (start_row = 0; start_row < (CAL_ROWS -
+ rect_height + 1); start_row++) {
+ unsigned ok = 1;
+ unsigned add_col, add_row;
+
+ /* Determine if the rectangle fits here */
+ for (add_col = 0; (add_col < rect_width) && ok;
+ add_col++) {
+ for (add_row = 0; add_row < rect_height;
+ add_row++) {
+ if (!cal_results
+ [start_row+add_row][start_col
+ + add_col]) {
+ ok = 0;
+ break;
+ }
+ }
+ }
+
+ /*
+ * Return 'middle' of rectangle in case of
+ * success
+ */
+ if (ok) {
+ if(rect_width > 1)
+ rect_width--;
+
+ if(rect_height > 1)
+ rect_height--;
+
+ *cal_row = start_row +
+ (rect_height / 2);
+ *cal_col = start_col + (rect_width / 2);
+
+ return 0;
+ }
+ }
+ }
+ }
+
+ /* We could not fit any rectangle - return failure */
+ return 1;
+}

+void socfpga_dwmmc_set_clksel(unsigned int drvsel, unsigned int smplsel)
+{
/* Disable SDMMC clock. */
clrbits_le32(&clock_manager_base->per_pll.en,
CLKMGR_PERPLLGRP_EN_SDMMCCLK_MASK);

- /* Configures drv_sel and smpl_sel */
- drvsel = CONFIG_SOCFPGA_DWMMC_DRVSEL;
- smplsel = CONFIG_SOCFPGA_DWMMC_SMPSEL;
-
debug("%s: drvsel %d smplsel %d\n", __func__, drvsel, smplsel);
writel(SYSMGR_SDMMC_CTRL_SET(smplsel, drvsel),
&system_manager_base->sdmmcgrp_ctrl);
@@ -42,6 +157,64 @@ static void socfpga_dwmci_clksel(struct dwmci_host *host)
CLKMGR_PERPLLGRP_EN_SDMMCCLK_MASK);
}

+/*
+ * This functions calirates the drvsel and smplsel by trying all possible
+ * values and selecting the best combnation
+ */
+void socfpga_dwmmc_calibrate(struct dwmci_host *host)
+{
+ int err = 0;
+ unsigned char cal_results[CAL_ROWS][CAL_COLS];
+ unsigned int sum = 0;
+ unsigned int row, col, drvsel, smplsel;
+
+ struct mmc *mmc = (struct mmc *)host->mmc;
+ if (mmc == NULL) {
+ printf("struct mmc is NULL\n");
+ hang();
+ }
+
+ printf("%s: Calibration started.\n", __func__);
+
+ for (row = 0; row < CAL_ROWS; row++) {
+ for (col = 0; col < CAL_COLS; col++) {
+ drvsel = row + 1;
+ smplsel = col;
+ socfpga_dwmmc_set_clksel(drvsel, smplsel);
+ cal_results[row][col] = !(mmc_set_blocklen(mmc,
+ mmc->read_bl_len));
+ sum += cal_results[row][col];
+ }
+ }
+
+ debug("%s: Calibration raw data:\n", __func__);
+ for(row = 0; row < CAL_ROWS; row++) {
+ debug("\t");
+ for(col = 0; col < CAL_COLS; col++)
+ debug("%d ", cal_results[row][col]);
+ debug("\n");
+ }
+
+ err = find_calibration_point(cal_results, sum, &drvsel, &smplsel);
+
+ if(err) {
+ printf("%s: Calibration failed.\n", __func__);
+ hang();
+ } else
+ printf("%s: Calibration passed: drvsel = %d "
+ "smplsel = %d.\n", __func__, drvsel, smplsel);
+
+ socfpga_dwmmc_set_clksel(drvsel, smplsel);
+
+ /* re-write in case accidentally overwrite with junk */
+ mmc_set_blocklen(mmc, mmc->read_bl_len);
+}
+
+void socfpga_dwmci_clksel(struct dwmci_host *host)
+{
+ socfpga_dwmmc_calibrate(host);
+}
+
int socfpga_dwmmc_init(u32 regbase, int bus_width, int index)
{
struct dwmci_host *host;
--
1.7.7.4