[U-Boot] [PATCH] Streamlined mpc512x fixed_sdram init sequence.
Signed-off-by: Martha M Stan mmarx@silicontkx.com --- board/davedenx/aria/aria.c | 2 +- board/esd/mecp5123/mecp5123.c | 2 +- board/freescale/mpc5121ads/mpc5121ads.c | 2 +- cpu/mpc512x/fixed_sdram.c | 104 ++++++++++++++++++++---------- include/asm-ppc/immap_512x.h | 4 + include/asm-ppc/mpc512x.h | 2 +- include/configs/aria.h | 22 +++---- include/configs/mecp5123.h | 23 +++---- include/configs/mpc5121ads.h | 30 ++++----- 9 files changed, 109 insertions(+), 82 deletions(-)
diff --git a/board/davedenx/aria/aria.c b/board/davedenx/aria/aria.c index 2064aa2..cc69c9d 100644 --- a/board/davedenx/aria/aria.c +++ b/board/davedenx/aria/aria.c @@ -101,7 +101,7 @@ int board_early_init_f(void)
phys_size_t initdram (int board_type) { - return fixed_sdram(); + return fixed_sdram(NULL, NULL, 0); }
int misc_init_r(void) diff --git a/board/esd/mecp5123/mecp5123.c b/board/esd/mecp5123/mecp5123.c index f591e32..5139358 100644 --- a/board/esd/mecp5123/mecp5123.c +++ b/board/esd/mecp5123/mecp5123.c @@ -135,7 +135,7 @@ int board_early_init_f(void)
phys_size_t initdram(int board_type) { - return get_ram_size(0, fixed_sdram()); + return get_ram_size(0, fixed_sdram(NULL, NULL, 0)); }
int misc_init_r(void) diff --git a/board/freescale/mpc5121ads/mpc5121ads.c b/board/freescale/mpc5121ads/mpc5121ads.c index a0d7a82..8defb00 100644 --- a/board/freescale/mpc5121ads/mpc5121ads.c +++ b/board/freescale/mpc5121ads/mpc5121ads.c @@ -137,7 +137,7 @@ phys_size_t initdram(int board_type) { u32 msize = 0;
- msize = fixed_sdram(); + msize = fixed_sdram(NULL, NULL, 0);
return msize; } diff --git a/cpu/mpc512x/fixed_sdram.c b/cpu/mpc512x/fixed_sdram.c index d906903..63a3035 100644 --- a/cpu/mpc512x/fixed_sdram.c +++ b/cpu/mpc512x/fixed_sdram.c @@ -25,18 +25,70 @@ #include <asm/io.h> #include <asm/mpc512x.h>
+/* + * MDDRC Config Runtime Settings in order of the 4 MDDRC cfg registers + */ +u32 default_mddrc_config[4] = { + CONFIG_SYS_MDDRC_SYS_CFG, + CONFIG_SYS_MDDRC_TIME_CFG0, + CONFIG_SYS_MDDRC_TIME_CFG1, + CONFIG_SYS_MDDRC_TIME_CFG2 +}; + +u32 default_init_seq[] = { + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_PCHG_ALL, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_RFSH, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_RFSH, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_MICRON_INIT_DEV_OP, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_EM2, + CONFIG_SYS_DDRCMD_NOP, + CONFIG_SYS_DDRCMD_PCHG_ALL, + CONFIG_SYS_DDRCMD_EM2, + CONFIG_SYS_DDRCMD_EM3, + CONFIG_SYS_DDRCMD_EN_DLL, + CONFIG_SYS_MICRON_INIT_DEV_OP, + CONFIG_SYS_DDRCMD_PCHG_ALL, + CONFIG_SYS_DDRCMD_RFSH, + CONFIG_SYS_MICRON_INIT_DEV_OP, + CONFIG_SYS_DDRCMD_OCD_DEFAULT, + CONFIG_SYS_DDRCMD_PCHG_ALL, + CONFIG_SYS_DDRCMD_NOP +}; + /* * fixed sdram init: * The board doesn't use memory modules that have serial presence * detect or similar mechanism for discovery of the DRAM settings */ -long int fixed_sdram(void) +long int fixed_sdram(u32 *mddrc_config, u32 *dram_init_seq, int seq_sz) { volatile immap_t *im = (immap_t *)CONFIG_SYS_IMMR; u32 msize = CONFIG_SYS_DDR_SIZE * 1024 * 1024; u32 msize_log2 = __ilog2(msize); u32 i;
+ /* take default settings and init sequence if necessary */ + if (mddrc_config == 0) + mddrc_config = default_mddrc_config; + if (dram_init_seq == 0) { + dram_init_seq = default_init_seq; + seq_sz = sizeof(default_init_seq)/sizeof(u32); + } + /* Initialize IO Control */ out_be32(&im->io_ctrl.io_control_mem, IOCTRL_MUX_DDR);
@@ -45,8 +97,8 @@ long int fixed_sdram(void) out_be32(&im->sysconf.ddrlaw.ar, msize_log2 - 1); sync_law(&im->sysconf.ddrlaw.ar);
- /* Enable DDR */ - out_be32(&im->mddrc.ddr_sys_config, CONFIG_SYS_MDDRC_SYS_CFG_EN); + /* DDR Enable */ + out_be32(&im->mddrc.ddr_sys_config, MDDRC_SYS_CFG_EN);
/* Initialize DDR Priority Manager */ out_be32(&im->mddrc.prioman_config1, CONFIG_SYS_MDDRCGRP_PM_CFG1); @@ -73,41 +125,23 @@ long int fixed_sdram(void) out_be32(&im->mddrc.lut_table4_alternate_upper, CONFIG_SYS_MDDRCGRP_LUT4_AU); out_be32(&im->mddrc.lut_table4_alternate_lower, CONFIG_SYS_MDDRCGRP_LUT4_AL);
- /* Initialize MDDRC */ - out_be32(&im->mddrc.ddr_sys_config, CONFIG_SYS_MDDRC_SYS_CFG); - out_be32(&im->mddrc.ddr_time_config0, CONFIG_SYS_MDDRC_TIME_CFG0); - out_be32(&im->mddrc.ddr_time_config1, CONFIG_SYS_MDDRC_TIME_CFG1); - out_be32(&im->mddrc.ddr_time_config2, CONFIG_SYS_MDDRC_TIME_CFG2); - - /* Initialize DDR */ - for (i = 0; i < 10; i++) - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_NOP); + /* + * Initialize MDDRC + * put MDDRC in CMD mode and + * set the max time between refreshes to 0 during init process + */ + out_be32(&im->mddrc.ddr_sys_config, mddrc_config[0] | MDDRC_SYS_CFG_CMD_MASK); + out_be32(&im->mddrc.ddr_time_config0, mddrc_config[1] & MDDRC_REFRESH_ZERO_MASK); + out_be32(&im->mddrc.ddr_time_config1, mddrc_config[2]); + out_be32(&im->mddrc.ddr_time_config2, mddrc_config[3]);
- out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_PCHG_ALL); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_NOP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_RFSH); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_NOP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_RFSH); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_NOP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_INIT_DEV_OP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_NOP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_EM2); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_NOP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_PCHG_ALL); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_EM2); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_EM3); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_EN_DLL); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_INIT_DEV_OP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_PCHG_ALL); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_RFSH); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_INIT_DEV_OP); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_OCD_DEFAULT); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_PCHG_ALL); - out_be32(&im->mddrc.ddr_command, CONFIG_SYS_MICRON_NOP); + /* Initialize DDR with either default or supplied init sequence */ + for (i = 0; i < seq_sz; i++) + out_be32(&im->mddrc.ddr_command, dram_init_seq[i]);
/* Start MDDRC */ - out_be32(&im->mddrc.ddr_time_config0, CONFIG_SYS_MDDRC_TIME_CFG0_RUN); - out_be32(&im->mddrc.ddr_sys_config, CONFIG_SYS_MDDRC_SYS_CFG_RUN); + out_be32(&im->mddrc.ddr_time_config0, mddrc_config[1]); + out_be32(&im->mddrc.ddr_sys_config, mddrc_config[0]);
return msize; } diff --git a/include/asm-ppc/immap_512x.h b/include/asm-ppc/immap_512x.h index 24e6c69..79cdd80 100644 --- a/include/asm-ppc/immap_512x.h +++ b/include/asm-ppc/immap_512x.h @@ -341,6 +341,10 @@ typedef struct ddr512x { u32 res2[0x3AD]; } ddr512x_t;
+/* MDDRC SYS CFG and Timing CFG0 Registers */ +#define MDDRC_SYS_CFG_EN 0xF0000000 +#define MDDRC_SYS_CFG_CMD_MASK 0x10000000 +#define MDDRC_REFRESH_ZERO_MASK 0x0000FFFF
/* * DMA/Messaging Unit diff --git a/include/asm-ppc/mpc512x.h b/include/asm-ppc/mpc512x.h index 20456f5..8ef0d9c 100644 --- a/include/asm-ppc/mpc512x.h +++ b/include/asm-ppc/mpc512x.h @@ -50,7 +50,7 @@ static inline void sync_law(volatile void *addr) /* * Prototypes */ -extern long int fixed_sdram(void); +extern long int fixed_sdram(u32 *mddrc_config, u32 *dram_init_seq, int seq_sz); extern int mpc5121_diu_init(void); extern void ide_set_reset(int idereset);
diff --git a/include/configs/aria.h b/include/configs/aria.h index 4211113..2938eac 100644 --- a/include/configs/aria.h +++ b/include/configs/aria.h @@ -126,7 +126,7 @@ #define CONFIG_SYS_MDDRC_SYS_CFG ( (1 << 31) | /* RST_B */ \ (1 << 30) | /* CKE */ \ (1 << 29) | /* CLK_ON */ \ - (1 << 28) | /* CMD_MODE */ \ + (0 << 28) | /* CMD_MODE */ \ (4 << 25) | /* DRAM_ROW_SELECT */ \ (3 << 21) | /* DRAM_BANK_SELECT */ \ (0 << 18) | /* SELF_REF_EN */ \ @@ -143,16 +143,12 @@ (0 << 0) /* FIFO_UV_EN */ \ )
-#define CONFIG_SYS_MDDRC_SYS_CFG_RUN (CONFIG_SYS_MDDRC_SYS_CFG & ~(1 << 28)) +#define CONFIG_SYS_MDDRC_TIME_CFG0 0x030C3D2E #define CONFIG_SYS_MDDRC_TIME_CFG1 0x55D81189 #define CONFIG_SYS_MDDRC_TIME_CFG2 0x34790863
-#define CONFIG_SYS_MDDRC_SYS_CFG_EN 0xF0000000 -#define CONFIG_SYS_MDDRC_TIME_CFG0 0x00003D2E -#define CONFIG_SYS_MDDRC_TIME_CFG0_RUN 0x030C3D2E - -#define CONFIG_SYS_MICRON_NOP 0x01380000 -#define CONFIG_SYS_MICRON_PCHG_ALL 0x01100400 +#define CONFIG_SYS_DDRCMD_NOP 0x01380000 +#define CONFIG_SYS_DDRCMD_PCHG_ALL 0x01100400 #define CONFIG_SYS_MICRON_EMR ( (1 << 24) | /* CMD_REQ */ \ (0 << 22) | /* DRAM_CS */ \ (0 << 21) | /* DRAM_RAS */ \ @@ -172,7 +168,7 @@ ) #define CONFIG_SYS_MICRON_EMR2 0x01020000 #define CONFIG_SYS_MICRON_EMR3 0x01030000 -#define CONFIG_SYS_MICRON_RFSH 0x01080000 +#define CONFIG_SYS_DDRCMD_RFSH 0x01080000 #define CONFIG_SYS_MICRON_INIT_DEV_OP 0x01000432 #define CONFIG_SYS_MICRON_EMR_OCD ( (1 << 24) | /* CMD_REQ */ \ (0 << 22) | /* DRAM_CS */ \ @@ -196,10 +192,10 @@ * Backward compatible definitions, * so we do not have to change cpu/mpc512x/fixed_sdram.c */ -#define CONFIG_SYS_MICRON_EM2 (CONFIG_SYS_MICRON_EMR2) -#define CONFIG_SYS_MICRON_EM3 (CONFIG_SYS_MICRON_EMR3) -#define CONFIG_SYS_MICRON_EN_DLL (CONFIG_SYS_MICRON_EMR) -#define CONFIG_SYS_MICRON_OCD_DEFAULT (CONFIG_SYS_MICRON_EMR_OCD) +#define CONFIG_SYS_DDRCMD_EM2 (CONFIG_SYS_MICRON_EMR2) +#define CONFIG_SYS_DDRCMD_EM3 (CONFIG_SYS_MICRON_EMR3) +#define CONFIG_SYS_DDRCMD_EN_DLL (CONFIG_SYS_MICRON_EMR) +#define CONFIG_SYS_DDRCMD_OCD_DEFAULT (CONFIG_SYS_MICRON_EMR_OCD)
/* DDR Priority Manager Configuration */ #define CONFIG_SYS_MDDRCGRP_PM_CFG1 0x00077777 diff --git a/include/configs/mecp5123.h b/include/configs/mecp5123.h index 1ecae00..e194c8f 100644 --- a/include/configs/mecp5123.h +++ b/include/configs/mecp5123.h @@ -111,22 +111,19 @@ * [09:05] DRAM tRP: * [04:00] DRAM tRPA */ -#define CONFIG_SYS_MDDRC_SYS_CFG 0xFA804A00 -#define CONFIG_SYS_MDDRC_SYS_CFG_RUN 0xEA804A00 +#define CONFIG_SYS_MDDRC_SYS_CFG 0xEA804A00 +#define CONFIG_SYS_MDDRC_TIME_CFG0 0x06183D2E #define CONFIG_SYS_MDDRC_TIME_CFG1 0x68EC1168 #define CONFIG_SYS_MDDRC_TIME_CFG2 0x34310864 -#define CONFIG_SYS_MDDRC_SYS_CFG_EN 0xF0000000 -#define CONFIG_SYS_MDDRC_TIME_CFG0 0x00003D2E -#define CONFIG_SYS_MDDRC_TIME_CFG0_RUN 0x06183D2E - -#define CONFIG_SYS_MICRON_NOP 0x01380000 -#define CONFIG_SYS_MICRON_PCHG_ALL 0x01100400 -#define CONFIG_SYS_MICRON_EM2 0x01020000 -#define CONFIG_SYS_MICRON_EM3 0x01030000 -#define CONFIG_SYS_MICRON_EN_DLL 0x01010000 -#define CONFIG_SYS_MICRON_RFSH 0x01080000 + +#define CONFIG_SYS_DDRCMD_NOP 0x01380000 +#define CONFIG_SYS_DDRCMD_PCHG_ALL 0x01100400 +#define CONFIG_SYS_DDRCMD_EM2 0x01020000 +#define CONFIG_SYS_DDRCMD_EM3 0x01030000 +#define CONFIG_SYS_DDRCMD_EN_DLL 0x01010000 +#define CONFIG_SYS_DDRCMD_RFSH 0x01080000 #define CONFIG_SYS_MICRON_INIT_DEV_OP 0x01000432 -#define CONFIG_SYS_MICRON_OCD_DEFAULT 0x01010780 +#define CONFIG_SYS_DDRCMD_OCD_DEFAULT 0x01010780
/* DDR Priority Manager Configuration */ #define CONFIG_SYS_MDDRCGRP_PM_CFG1 0x00077777 diff --git a/include/configs/mpc5121ads.h b/include/configs/mpc5121ads.h index 76f174d..0c871c9 100644 --- a/include/configs/mpc5121ads.h +++ b/include/configs/mpc5121ads.h @@ -131,28 +131,24 @@ * [04:00] DRAM tRPA */ #ifdef CONFIG_MPC5121ADS_REV2 -#define CONFIG_SYS_MDDRC_SYS_CFG 0xF8604A00 -#define CONFIG_SYS_MDDRC_SYS_CFG_RUN 0xE8604A00 +#define CONFIG_SYS_MDDRC_SYS_CFG 0xE8604A00 #define CONFIG_SYS_MDDRC_TIME_CFG1 0x54EC1168 #define CONFIG_SYS_MDDRC_TIME_CFG2 0x35210864 #else -#define CONFIG_SYS_MDDRC_SYS_CFG 0xFA804A00 -#define CONFIG_SYS_MDDRC_SYS_CFG_RUN 0xEA804A00 -#define CONFIG_SYS_MDDRC_TIME_CFG1 0x68EC1168 -#define CONFIG_SYS_MDDRC_TIME_CFG2 0x34310864 +#define CONFIG_SYS_MDDRC_SYS_CFG 0xEA804A00 +#define CONFIG_SYS_MDDRC_TIME_CFG1 0x68EC1168 +#define CONFIG_SYS_MDDRC_TIME_CFG2 0x34310864 #endif -#define CONFIG_SYS_MDDRC_SYS_CFG_EN 0xF0000000 -#define CONFIG_SYS_MDDRC_TIME_CFG0 0x00003D2E -#define CONFIG_SYS_MDDRC_TIME_CFG0_RUN 0x06183D2E - -#define CONFIG_SYS_MICRON_NOP 0x01380000 -#define CONFIG_SYS_MICRON_PCHG_ALL 0x01100400 -#define CONFIG_SYS_MICRON_EM2 0x01020000 -#define CONFIG_SYS_MICRON_EM3 0x01030000 -#define CONFIG_SYS_MICRON_EN_DLL 0x01010000 -#define CONFIG_SYS_MICRON_RFSH 0x01080000 +#define CONFIG_SYS_MDDRC_TIME_CFG0 0x06183D2E + +#define CONFIG_SYS_DDRCMD_NOP 0x01380000 +#define CONFIG_SYS_DDRCMD_PCHG_ALL 0x01100400 +#define CONFIG_SYS_DDRCMD_EM2 0x01020000 +#define CONFIG_SYS_DDRCMD_EM3 0x01030000 +#define CONFIG_SYS_DDRCMD_EN_DLL 0x01010000 +#define CONFIG_SYS_DDRCMD_RFSH 0x01080000 #define CONFIG_SYS_MICRON_INIT_DEV_OP 0x01000432 -#define CONFIG_SYS_MICRON_OCD_DEFAULT 0x01010780 +#define CONFIG_SYS_DDRCMD_OCD_DEFAULT 0x01010780
/* DDR Priority Manager Configuration */ #define CONFIG_SYS_MDDRCGRP_PM_CFG1 0x00077777
Dear Martha M Stan,
In message 12535564342520-git-send-email-mmarx@silicontkx.com you wrote:
Signed-off-by: Martha M Stan mmarx@silicontkx.com
board/davedenx/aria/aria.c | 2 +- board/esd/mecp5123/mecp5123.c | 2 +- board/freescale/mpc5121ads/mpc5121ads.c | 2 +- cpu/mpc512x/fixed_sdram.c | 104 ++++++++++++++++++++---------- include/asm-ppc/immap_512x.h | 4 + include/asm-ppc/mpc512x.h | 2 +- include/configs/aria.h | 22 +++---- include/configs/mecp5123.h | 23 +++---- include/configs/mpc5121ads.h | 30 ++++----- 9 files changed, 109 insertions(+), 82 deletions(-)
Applying: Streamlined mpc512x fixed_sdram init sequence. /home/wd/git/u-boot/work/.git/rebase-apply/patch:60: trailing whitespace. /* /home/wd/git/u-boot/work/.git/rebase-apply/patch:61: trailing whitespace. * MDDRC Config Runtime Settings in order of the 4 MDDRC cfg registers /home/wd/git/u-boot/work/.git/rebase-apply/patch:152: trailing whitespace. /* /home/wd/git/u-boot/work/.git/rebase-apply/patch:154: trailing whitespace. * put MDDRC in CMD mode and /home/wd/git/u-boot/work/.git/rebase-apply/patch:155: trailing whitespace. * set the max time between refreshes to 0 during init process warning: 5 lines applied after fixing whitespace errors.
Please pay more attention to Coding Style!
diff --git a/cpu/mpc512x/fixed_sdram.c b/cpu/mpc512x/fixed_sdram.c index d906903..63a3035 100644 --- a/cpu/mpc512x/fixed_sdram.c +++ b/cpu/mpc512x/fixed_sdram.c @@ -25,18 +25,70 @@ #include <asm/io.h> #include <asm/mpc512x.h>
+/*
- MDDRC Config Runtime Settings in order of the 4 MDDRC cfg registers
- */
+u32 default_mddrc_config[4] = {
- CONFIG_SYS_MDDRC_SYS_CFG,
- CONFIG_SYS_MDDRC_TIME_CFG0,
- CONFIG_SYS_MDDRC_TIME_CFG1,
- CONFIG_SYS_MDDRC_TIME_CFG2
+};
Hm... we should move the first entry down... see below...
-long int fixed_sdram(void) +long int fixed_sdram(u32 *mddrc_config, u32 *dram_init_seq, int seq_sz) { volatile immap_t *im = (immap_t *)CONFIG_SYS_IMMR; u32 msize = CONFIG_SYS_DDR_SIZE * 1024 * 1024; u32 msize_log2 = __ilog2(msize); u32 i;
- /* take default settings and init sequence if necessary */
- if (mddrc_config == 0)
mddrc_config = default_mddrc_config;
Please write NULL when you mean a NULL pointer.
- if (dram_init_seq == 0) {
dram_init_seq = default_init_seq;seq_sz = sizeof(default_init_seq)/sizeof(u32);- }
Ditto.
- /*
* Initialize MDDRC* put MDDRC in CMD mode and* set the max time between refreshes to 0 during init process*/- out_be32(&im->mddrc.ddr_sys_config, mddrc_config[0] | MDDRC_SYS_CFG_CMD_MASK);
- out_be32(&im->mddrc.ddr_time_config0, mddrc_config[1] & MDDRC_REFRESH_ZERO_MASK);
- out_be32(&im->mddrc.ddr_time_config1, mddrc_config[2]);
- out_be32(&im->mddrc.ddr_time_config2, mddrc_config[3]);
I cannot help it, but every time I see this I think the code is wrong. Guess I have seen too many copy & paste errors in this style. When I see "...time_config2" I also want to see "mddrc_config[2]", i. e. identical indices. We should reorder the struct.
To make some progress, I made the changes above, and applied the patch.
Thanks.
Best regards,
Wolfgang Denk
participants (2)
-
Martha M Stan -
Wolfgang Denk