mmc: atmel-mci: add support for odd clock dividers
Ludovic Desroches [Wed, 21 Mar 2012 15:41:23 +0000 (16:41 +0100)]
Add an odd clock divider capability available from v5xx. It also involves
changing the clock divider calculation, and changing the switch-case
statement to use top-down fallthrough.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/atmel-mci-regs.h
drivers/mmc/host/atmel-mci.c

index 000b3ad..787aba1 100644 (file)
@@ -31,6 +31,7 @@
 # define ATMCI_MR_PDCFBYTE             (  1 << 13)     /* Force Byte Transfer */
 # define ATMCI_MR_PDCPADV              (  1 << 14)     /* Padding Value */
 # define ATMCI_MR_PDCMODE              (  1 << 15)     /* PDC-oriented Mode */
+# define ATMCI_MR_CLKODD(x)            ((x) << 16)     /* LSB of Clock Divider */
 #define ATMCI_DTOR                     0x0008  /* Data Timeout */
 # define ATMCI_DTOCYC(x)               ((x) <<  0)     /* Data Timeout Cycles */
 # define ATMCI_DTOMUL(x)               ((x) <<  4)     /* Data Timeout Multiplier */
index c56edc4..e94476b 100644 (file)
@@ -77,6 +77,7 @@ struct atmel_mci_caps {
        bool    has_cstor_reg;
        bool    has_highspeed;
        bool    has_rwproof;
+       bool    has_odd_clk_div;
 };
 
 struct atmel_mci_dma {
@@ -1134,16 +1135,27 @@ static void atmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                }
 
                /* Calculate clock divider */
-               clkdiv = DIV_ROUND_UP(host->bus_hz, 2 * clock_min) - 1;
-               if (clkdiv > 255) {
-                       dev_warn(&mmc->class_dev,
-                               "clock %u too slow; using %lu\n",
-                               clock_min, host->bus_hz / (2 * 256));
-                       clkdiv = 255;
+               if (host->caps.has_odd_clk_div) {
+                       clkdiv = DIV_ROUND_UP(host->bus_hz, clock_min) - 2;
+                       if (clkdiv > 511) {
+                               dev_warn(&mmc->class_dev,
+                                        "clock %u too slow; using %lu\n",
+                                        clock_min, host->bus_hz / (511 + 2));
+                               clkdiv = 511;
+                       }
+                       host->mode_reg = ATMCI_MR_CLKDIV(clkdiv >> 1)
+                                        | ATMCI_MR_CLKODD(clkdiv & 1);
+               } else {
+                       clkdiv = DIV_ROUND_UP(host->bus_hz, 2 * clock_min) - 1;
+                       if (clkdiv > 255) {
+                               dev_warn(&mmc->class_dev,
+                                        "clock %u too slow; using %lu\n",
+                                        clock_min, host->bus_hz / (2 * 256));
+                               clkdiv = 255;
+                       }
+                       host->mode_reg = ATMCI_MR_CLKDIV(clkdiv);
                }
 
-               host->mode_reg = ATMCI_MR_CLKDIV(clkdiv);
-
                /*
                 * WRPROOF and RDPROOF prevent overruns/underruns by
                 * stopping the clock when the FIFO is full/empty.
@@ -2014,37 +2026,35 @@ static void __init atmci_get_cap(struct atmel_mci *host)
                        "version: 0x%x\n", version);
 
        host->caps.has_dma = 0;
-       host->caps.has_pdc = 0;
+       host->caps.has_pdc = 1;
        host->caps.has_cfg_reg = 0;
        host->caps.has_cstor_reg = 0;
        host->caps.has_highspeed = 0;
        host->caps.has_rwproof = 0;
+       host->caps.has_odd_clk_div = 0;
 
        /* keep only major version number */
        switch (version & 0xf00) {
-       case 0x100:
-               host->caps.has_pdc = 1;
-               break;
-       case 0x200:
-               host->caps.has_pdc = 1;
-               host->caps.has_rwproof = 1;
-               break;
-       case 0x300:
-       case 0x400:
        case 0x500:
+               host->caps.has_odd_clk_div = 1;
+       case 0x400:
+       case 0x300:
 #ifdef CONFIG_AT_HDMAC
                host->caps.has_dma = 1;
 #else
-               host->caps.has_dma = 0;
                dev_info(&host->pdev->dev,
                        "has dma capability but dma engine is not selected, then use pio\n");
 #endif
+               host->caps.has_pdc = 0;
                host->caps.has_cfg_reg = 1;
                host->caps.has_cstor_reg = 1;
                host->caps.has_highspeed = 1;
+       case 0x200:
                host->caps.has_rwproof = 1;
+       case 0x100:
                break;
        default:
+               host->caps.has_pdc = 0;
                dev_warn(&host->pdev->dev,
                                "Unmanaged mci version, set minimum capabilities\n");
                break;