ARM: OMAP4: VC: setup I2C parameters based on board data

VC code now provides a table of pre-calculated I2C setup parameters, which will be used based on the capacitance value calculated for the I2C trace on the PCB. A default trace length of 6.3cm is used unless board defines its own value during init. The parameters set will be the I2C internal pull setup and the I2C timing parameters for high speed use mode. Full speed mode is not supported as of now. Signed-off-by: Tero Kristo <t-kristo@ti.com> Signed-off-by: Kevin Hilman <khilman@ti.com>

ARM: OMAP4: VC: setup I2C parameters based on board data
VC code now provides a table of pre-calculated I2C setup parameters, which will be used based on the capacitance value calculated for the I2C trace on the PCB. A default trace length of 6.3cm is used unless board defines its own value during init. The parameters set will be the I2C internal pull setup and the I2C timing parameters for high speed use mode. Full speed mode is not supported as of now. Signed-off-by: Tero Kristo <t-kristo@ti.com> Signed-off-by: Kevin Hilman <khilman@ti.com>
Tero Kristo · Kevin Hilman
1 parent 2ceec7b25c
Showing 4 changed files with 147 additions and 8 deletions Side-by-side Diff
arch/arm/mach-omap2/omap_twl.c
arch/arm/mach-omap2/pm.h
arch/arm/mach-omap2/vc.c
arch/arm/mach-omap2/voltage.h
@@ -183,6 +183,7 @@
 	.volt_reg_addr		= OMAP4_VDD_MPU_SR_VOLT_REG,
 	.cmd_reg_addr		= OMAP4_VDD_MPU_SR_CMD_REG,
 	.i2c_high_speed		= true,
+	.i2c_pad_load		= 3,
 	.vsel_to_uv		= twl6030_vsel_to_uv,
 	.uv_to_vsel		= twl6030_uv_to_vsel,
 };
@@ -200,6 +201,7 @@
 	.volt_reg_addr		= OMAP4_VDD_IVA_SR_VOLT_REG,
 	.cmd_reg_addr		= OMAP4_VDD_IVA_SR_CMD_REG,
 	.i2c_high_speed		= true,
+	.i2c_pad_load		= 3,
 	.vsel_to_uv		= twl6030_vsel_to_uv,
 	.uv_to_vsel		= twl6030_uv_to_vsel,
 };
@@ -216,6 +218,7 @@
 	.i2c_slave_addr		= OMAP4_SRI2C_SLAVE_ADDR,
 	.volt_reg_addr		= OMAP4_VDD_CORE_SR_VOLT_REG,
 	.cmd_reg_addr		= OMAP4_VDD_CORE_SR_CMD_REG,
+	.i2c_pad_load		= 3,
 	.vsel_to_uv		= twl6030_vsel_to_uv,
 	.uv_to_vsel		= twl6030_uv_to_vsel,
 };
@@ -132,9 +132,11 @@
 #ifdef CONFIG_PM
 extern void omap_pm_setup_oscillator(u32 tstart, u32 tshut);
 extern void omap_pm_get_oscillator(u32 *tstart, u32 *tshut);
+extern void omap_pm_setup_sr_i2c_pcb_length(u32 mm);
 #else
 static inline void omap_pm_setup_oscillator(u32 tstart, u32 tshut) { }
 static inline void omap_pm_get_oscillator(u32 *tstart, u32 *tshut) { }
+static inline void omap_pm_setup_sr_i2c_pcb_length(u32 mm) { }
 #endif
  
 #endif
@@ -24,6 +24,7 @@
 #include "prm44xx.h"
 #include "pm.h"
 #include "scrm44xx.h"
+#include "control.h"
  
 /**
  * struct omap_vc_channel_cfg - describe the cfg_channel bitfield
@@ -69,6 +70,9 @@
 };
  
 static struct omap_vc_channel_cfg *vc_cfg_bits;
+
+/* Default I2C trace length on pcb, 6.3cm. Used for capacitance calculations. */
+static u32 sr_i2c_pcb_length = 63;
 #define CFG_CHANNEL_MASK 0x1f
  
 /**
  
  
  
  
  
  
@@ -464,22 +468,135 @@
 /* OMAP4 specific voltage init functions */
 static void __init omap4_vc_init_channel(struct voltagedomain *voltdm)
 {
-	static bool is_initialized;
-	u32 vc_val;
-
 	omap4_set_timings(voltdm, true);
 	omap4_set_timings(voltdm, false);
+}
  
-	if (is_initialized)
+struct i2c_init_data {
+	u8 loadbits;
+	u8 load;
+	u8 hsscll_38_4;
+	u8 hsscll_26;
+	u8 hsscll_19_2;
+	u8 hsscll_16_8;
+	u8 hsscll_12;
+};
+
+static const __initdata struct i2c_init_data omap4_i2c_timing_data[] = {
+	{
+		.load = 50,
+		.loadbits = 0x3,
+		.hsscll_38_4 = 13,
+		.hsscll_26 = 11,
+		.hsscll_19_2 = 9,
+		.hsscll_16_8 = 9,
+		.hsscll_12 = 8,
+	},
+	{
+		.load = 25,
+		.loadbits = 0x2,
+		.hsscll_38_4 = 13,
+		.hsscll_26 = 11,
+		.hsscll_19_2 = 9,
+		.hsscll_16_8 = 9,
+		.hsscll_12 = 8,
+	},
+	{
+		.load = 12,
+		.loadbits = 0x1,
+		.hsscll_38_4 = 11,
+		.hsscll_26 = 10,
+		.hsscll_19_2 = 9,
+		.hsscll_16_8 = 9,
+		.hsscll_12 = 8,
+	},
+	{
+		.load = 0,
+		.loadbits = 0x0,
+		.hsscll_38_4 = 12,
+		.hsscll_26 = 10,
+		.hsscll_19_2 = 9,
+		.hsscll_16_8 = 8,
+		.hsscll_12 = 8,
+	},
+};
+
+/**
+ * omap4_vc_i2c_timing_init - sets up board I2C timing parameters
+ * @voltdm: voltagedomain pointer to get data from
+ *
+ * Use PMIC + board supplied settings for calculating the total I2C
+ * channel capacitance and set the timing parameters based on this.
+ * Pre-calculated values are provided in data tables, as it is not
+ * too straightforward to calculate these runtime.
+ */
+static void __init omap4_vc_i2c_timing_init(struct voltagedomain *voltdm)
+{
+	u32 capacitance;
+	u32 val;
+	u16 hsscll;
+	const struct i2c_init_data *i2c_data;
+
+	if (!voltdm->pmic->i2c_high_speed) {
+		pr_warn("%s: only high speed supported!\n", __func__);
 		return;
+	}
  
-	/* XXX These are magic numbers and do not belong! */
-	vc_val = (0x60 << OMAP4430_SCLL_SHIFT | 0x26 << OMAP4430_SCLH_SHIFT);
-	voltdm->write(vc_val, OMAP4_PRM_VC_CFG_I2C_CLK_OFFSET);
+	/* PCB trace capacitance, 0.125pF / mm => mm / 8 */
+	capacitance = DIV_ROUND_UP(sr_i2c_pcb_length, 8);
  
-	is_initialized = true;
+	/* OMAP pad capacitance */
+	capacitance += 4;
+
+	/* PMIC pad capacitance */
+	capacitance += voltdm->pmic->i2c_pad_load;
+
+	/* Search for capacitance match in the table */
+	i2c_data = omap4_i2c_timing_data;
+
+	while (i2c_data->load > capacitance)
+		i2c_data++;
+
+	/* Select proper values based on sysclk frequency */
+	switch (voltdm->sys_clk.rate) {
+	case 38400000:
+		hsscll = i2c_data->hsscll_38_4;
+		break;
+	case 26000000:
+		hsscll = i2c_data->hsscll_26;
+		break;
+	case 19200000:
+		hsscll = i2c_data->hsscll_19_2;
+		break;
+	case 16800000:
+		hsscll = i2c_data->hsscll_16_8;
+		break;
+	case 12000000:
+		hsscll = i2c_data->hsscll_12;
+		break;
+	default:
+		pr_warn("%s: unsupported sysclk rate: %d!\n", __func__,
+			voltdm->sys_clk.rate);
+		return;
+	}
+
+	/* Loadbits define pull setup for the I2C channels */
+	val = i2c_data->loadbits << 25 | i2c_data->loadbits << 29;
+
+	/* Write to SYSCTRL_PADCONF_WKUP_CTRL_I2C_2 to setup I2C pull */
+	__raw_writel(val, OMAP2_L4_IO_ADDRESS(OMAP4_CTRL_MODULE_PAD_WKUP +
+				OMAP4_CTRL_MODULE_PAD_WKUP_CONTROL_I2C_2));
+
+	/* HSSCLH can always be zero */
+	val = hsscll << OMAP4430_HSSCLL_SHIFT;
+	val |= (0x28 << OMAP4430_SCLL_SHIFT | 0x2c << OMAP4430_SCLH_SHIFT);
+
+	/* Write setup times to I2C config register */
+	voltdm->write(val, OMAP4_PRM_VC_CFG_I2C_CLK_OFFSET);
 }
  
+
+
 /**
  * omap_vc_i2c_init - initialize I2C interface to PMIC
  * @voltdm: voltage domain containing VC data
@@ -519,6 +636,9 @@
 			    mcode << __ffs(vc->common->i2c_mcode_mask),
 			    vc->common->i2c_cfg_reg);
  
+	if (cpu_is_omap44xx())
+		omap4_vc_i2c_timing_init(voltdm);
+
 	initialized = true;
 }
  
@@ -544,6 +664,19 @@
 	}
  
 	return voltdm->pmic->uv_to_vsel(uvolt);
+}
+
+/**
+ * omap_pm_setup_sr_i2c_pcb_length - set length of SR I2C traces on PCB
+ * @mm: length of the PCB trace in millimetres
+ *
+ * Sets the PCB trace length for the I2C channel. By default uses 63mm.
+ * This is needed for properly calculating the capacitance value for
+ * the PCB trace, and for setting the SR I2C channel timing parameters.
+ */
+void __init omap_pm_setup_sr_i2c_pcb_length(u32 mm)
+{
+	sr_i2c_pcb_length = mm;
 }
  
 void __init omap_vc_init_channel(struct voltagedomain *voltdm)
@@ -139,6 +139,7 @@
 	u32 vddmax;
 	u8 vp_timeout_us;
 	bool i2c_high_speed;
+	u32 i2c_pad_load;
 	u8 i2c_mcode;
 	unsigned long (*vsel_to_uv) (const u8 vsel);
 	u8 (*uv_to_vsel) (unsigned long uV);
...	...	@@ -183,6 +183,7 @@
183	183	.volt_reg_addr = OMAP4_VDD_MPU_SR_VOLT_REG,
184	184	.cmd_reg_addr = OMAP4_VDD_MPU_SR_CMD_REG,
185	185	.i2c_high_speed = true,
	186	+ .i2c_pad_load = 3,
186	187	.vsel_to_uv = twl6030_vsel_to_uv,
187	188	.uv_to_vsel = twl6030_uv_to_vsel,
188	189	};
...	...	@@ -200,6 +201,7 @@
200	201	.volt_reg_addr = OMAP4_VDD_IVA_SR_VOLT_REG,
201	202	.cmd_reg_addr = OMAP4_VDD_IVA_SR_CMD_REG,
202	203	.i2c_high_speed = true,
	204	+ .i2c_pad_load = 3,
203	205	.vsel_to_uv = twl6030_vsel_to_uv,
204	206	.uv_to_vsel = twl6030_uv_to_vsel,
205	207	};
...	...	@@ -216,6 +218,7 @@
216	218	.i2c_slave_addr = OMAP4_SRI2C_SLAVE_ADDR,
217	219	.volt_reg_addr = OMAP4_VDD_CORE_SR_VOLT_REG,
218	220	.cmd_reg_addr = OMAP4_VDD_CORE_SR_CMD_REG,
	221	+ .i2c_pad_load = 3,
219	222	.vsel_to_uv = twl6030_vsel_to_uv,
220	223	.uv_to_vsel = twl6030_uv_to_vsel,
221	224	};
...	...	@@ -132,9 +132,11 @@
132	132	#ifdef CONFIG_PM
133	133	extern void omap_pm_setup_oscillator(u32 tstart, u32 tshut);
134	134	extern void omap_pm_get_oscillator(u32 tstart, u32 tshut);
	135	+extern void omap_pm_setup_sr_i2c_pcb_length(u32 mm);
135	136	#else
136	137	static inline void omap_pm_setup_oscillator(u32 tstart, u32 tshut) { }
137	138	static inline void omap_pm_get_oscillator(u32 tstart, u32 tshut) { }
	139	+static inline void omap_pm_setup_sr_i2c_pcb_length(u32 mm) { }
138	140	#endif
139	141
140	142	#endif
...	...	@@ -24,6 +24,7 @@
24	24	#include "prm44xx.h"
25	25	#include "pm.h"
26	26	#include "scrm44xx.h"
	27	+#include "control.h"
27	28
28	29	/**
29	30	* struct omap_vc_channel_cfg - describe the cfg_channel bitfield
...	...	@@ -69,6 +70,9 @@
69	70	};
70	71
71	72	static struct omap_vc_channel_cfg *vc_cfg_bits;
	73	+
	74	+/* Default I2C trace length on pcb, 6.3cm. Used for capacitance calculations. */
	75	+static u32 sr_i2c_pcb_length = 63;
72	76	#define CFG_CHANNEL_MASK 0x1f
73	77
74	78	/**
75	79
76	80
77	81
78	82
79	83
80	84
...	...	@@ -464,22 +468,135 @@
464	468	/* OMAP4 specific voltage init functions */
465	469	static void __init omap4_vc_init_channel(struct voltagedomain *voltdm)
466	470	{
467		- static bool is_initialized;
468		- u32 vc_val;
469		-
470	471	omap4_set_timings(voltdm, true);
471	472	omap4_set_timings(voltdm, false);
	473	+}
472	474
473		- if (is_initialized)
	475	+struct i2c_init_data {
	476	+ u8 loadbits;
	477	+ u8 load;
	478	+ u8 hsscll_38_4;
	479	+ u8 hsscll_26;
	480	+ u8 hsscll_19_2;
	481	+ u8 hsscll_16_8;
	482	+ u8 hsscll_12;
	483	+};
	484	+
	485	+static const __initdata struct i2c_init_data omap4_i2c_timing_data[] = {
	486	+ {
	487	+ .load = 50,
	488	+ .loadbits = 0x3,
	489	+ .hsscll_38_4 = 13,
	490	+ .hsscll_26 = 11,
	491	+ .hsscll_19_2 = 9,
	492	+ .hsscll_16_8 = 9,
	493	+ .hsscll_12 = 8,
	494	+ },
	495	+ {
	496	+ .load = 25,
	497	+ .loadbits = 0x2,
	498	+ .hsscll_38_4 = 13,
	499	+ .hsscll_26 = 11,
	500	+ .hsscll_19_2 = 9,
	501	+ .hsscll_16_8 = 9,
	502	+ .hsscll_12 = 8,
	503	+ },
	504	+ {
	505	+ .load = 12,
	506	+ .loadbits = 0x1,
	507	+ .hsscll_38_4 = 11,
	508	+ .hsscll_26 = 10,
	509	+ .hsscll_19_2 = 9,
	510	+ .hsscll_16_8 = 9,
	511	+ .hsscll_12 = 8,
	512	+ },
	513	+ {
	514	+ .load = 0,
	515	+ .loadbits = 0x0,
	516	+ .hsscll_38_4 = 12,
	517	+ .hsscll_26 = 10,
	518	+ .hsscll_19_2 = 9,
	519	+ .hsscll_16_8 = 8,
	520	+ .hsscll_12 = 8,
	521	+ },
	522	+};
	523	+
	524	+/**
	525	+ * omap4_vc_i2c_timing_init - sets up board I2C timing parameters
	526	+ * @voltdm: voltagedomain pointer to get data from
	527	+ *
	528	+ * Use PMIC + board supplied settings for calculating the total I2C
	529	+ * channel capacitance and set the timing parameters based on this.
	530	+ * Pre-calculated values are provided in data tables, as it is not
	531	+ * too straightforward to calculate these runtime.
	532	+ */
	533	+static void __init omap4_vc_i2c_timing_init(struct voltagedomain *voltdm)
	534	+{
	535	+ u32 capacitance;
	536	+ u32 val;
	537	+ u16 hsscll;
	538	+ const struct i2c_init_data *i2c_data;
	539	+
	540	+ if (!voltdm->pmic->i2c_high_speed) {
	541	+ pr_warn("%s: only high speed supported!\n", __func__);
474	542	return;
	543	+ }
475	544
476		- /* XXX These are magic numbers and do not belong! */
477		- vc_val = (0x60 << OMAP4430_SCLL_SHIFT \| 0x26 << OMAP4430_SCLH_SHIFT);
478		- voltdm->write(vc_val, OMAP4_PRM_VC_CFG_I2C_CLK_OFFSET);
	545	+ /* PCB trace capacitance, 0.125pF / mm => mm / 8 */
	546	+ capacitance = DIV_ROUND_UP(sr_i2c_pcb_length, 8);
479	547
480		- is_initialized = true;
	548	+ /* OMAP pad capacitance */
	549	+ capacitance += 4;
	550	+
	551	+ /* PMIC pad capacitance */
	552	+ capacitance += voltdm->pmic->i2c_pad_load;
	553	+
	554	+ /* Search for capacitance match in the table */
	555	+ i2c_data = omap4_i2c_timing_data;
	556	+
	557	+ while (i2c_data->load > capacitance)
	558	+ i2c_data++;
	559	+
	560	+ /* Select proper values based on sysclk frequency */
	561	+ switch (voltdm->sys_clk.rate) {
	562	+ case 38400000:
	563	+ hsscll = i2c_data->hsscll_38_4;
	564	+ break;
	565	+ case 26000000:
	566	+ hsscll = i2c_data->hsscll_26;
	567	+ break;
	568	+ case 19200000:
	569	+ hsscll = i2c_data->hsscll_19_2;
	570	+ break;
	571	+ case 16800000:
	572	+ hsscll = i2c_data->hsscll_16_8;
	573	+ break;
	574	+ case 12000000:
	575	+ hsscll = i2c_data->hsscll_12;
	576	+ break;
	577	+ default:
	578	+ pr_warn("%s: unsupported sysclk rate: %d!\n", __func__,
	579	+ voltdm->sys_clk.rate);
	580	+ return;
	581	+ }
	582	+
	583	+ /* Loadbits define pull setup for the I2C channels */
	584	+ val = i2c_data->loadbits << 25 \| i2c_data->loadbits << 29;
	585	+
	586	+ /* Write to SYSCTRL_PADCONF_WKUP_CTRL_I2C_2 to setup I2C pull */
	587	+ __raw_writel(val, OMAP2_L4_IO_ADDRESS(OMAP4_CTRL_MODULE_PAD_WKUP +
	588	+ OMAP4_CTRL_MODULE_PAD_WKUP_CONTROL_I2C_2));
	589	+
	590	+ /* HSSCLH can always be zero */
	591	+ val = hsscll << OMAP4430_HSSCLL_SHIFT;
	592	+ val \|= (0x28 << OMAP4430_SCLL_SHIFT \| 0x2c << OMAP4430_SCLH_SHIFT);
	593	+
	594	+ /* Write setup times to I2C config register */
	595	+ voltdm->write(val, OMAP4_PRM_VC_CFG_I2C_CLK_OFFSET);
481	596	}
482	597
	598	+
	599	+
483	600	/**
484	601	* omap_vc_i2c_init - initialize I2C interface to PMIC
485	602	* @voltdm: voltage domain containing VC data
...	...	@@ -519,6 +636,9 @@
519	636	mcode << __ffs(vc->common->i2c_mcode_mask),
520	637	vc->common->i2c_cfg_reg);
521	638
	639	+ if (cpu_is_omap44xx())
	640	+ omap4_vc_i2c_timing_init(voltdm);
	641	+
522	642	initialized = true;
523	643	}
524	644
...	...	@@ -544,6 +664,19 @@
544	664	}
545	665
546	666	return voltdm->pmic->uv_to_vsel(uvolt);
	667	+}
	668	+
	669	+/**
	670	+ * omap_pm_setup_sr_i2c_pcb_length - set length of SR I2C traces on PCB
	671	+ * @mm: length of the PCB trace in millimetres
	672	+ *
	673	+ * Sets the PCB trace length for the I2C channel. By default uses 63mm.
	674	+ * This is needed for properly calculating the capacitance value for
	675	+ * the PCB trace, and for setting the SR I2C channel timing parameters.
	676	+ */
	677	+void __init omap_pm_setup_sr_i2c_pcb_length(u32 mm)
	678	+{
	679	+ sr_i2c_pcb_length = mm;
547	680	}
548	681
549	682	void __init omap_vc_init_channel(struct voltagedomain *voltdm)
...	...	@@ -139,6 +139,7 @@
139	139	u32 vddmax;
140	140	u8 vp_timeout_us;
141	141	bool i2c_high_speed;
	142	+ u32 i2c_pad_load;
142	143	u8 i2c_mcode;
143	144	unsigned long (*vsel_to_uv) (const u8 vsel);
144	145	u8 (*uv_to_vsel) (unsigned long uV);